Homework Help: Science: Physics

Recent Homework Questions About Physics

physics
TV-reception antennas for VHF (channels 2 through 13) are constructed with cross wires supported at their centers, as shown in Figure 23.24. The ideal length for the cross wires is one-half the wavelength to be received, with the more expensive antennas having one for each ...
Tuesday, May 29, 2012 at 1:04pm

physics
Electromagnetic radiation having a 12.0 µm wavelength is classified as infrared radiation. What is its frequency? 1 Hz i got 1.31e+13???
Tuesday, May 29, 2012 at 1:04pm

physics
Citizen's band (CB) radio utilizes frequencies between commercial AM and FM. What is the frequency of a 11.34 m wavelength CB channel? 1 MHz How do you solve for MHz
Tuesday, May 29, 2012 at 1:03pm

physics
(a) Two microwave frequencies are authorized for use in microwave ovens: 900 and 2560 MHz. Calculate the wavelength of each. 1 cm (frequency = 900 MHz) 2 cm (frequency = 2560 MHz) (b) Which frequency would produce smaller hot spots in foods due to interference effects? 3 MHz
Tuesday, May 29, 2012 at 1:03pm

physics
if a period is doubled, than the length of the pendulum should be ? A) increased by root 2 b) quartered c) quadrupled d) halved e) doubled
Tuesday, May 29, 2012 at 8:36am

physics(heat)
A geyser heats water flowing at the rate of 3L/min from 27 deg C to 77 deg C. if the geyser operates on a burner, what is the rate of combustion of the fuel if its heat of combustion is 40000J/g?
Tuesday, May 29, 2012 at 3:16am

Physics
Ordinary glasses are worn in front of the eye and usually 2.00 cm in front of the eyeball. A certain person can see distant objects well, but his near point is 60.0 cm from his eyes instead of the usual 25.0 cm. Suppose that this person needs ordinary glasses. What focal ...
Tuesday, May 29, 2012 at 2:42am

physics(heat)
a mixture of 250g of water and 200g of ice at 0deg C is kept in a calorimeter which has a water equivalent of 50g. if 200g of steam at 100deg C is passed through this mixture, calculate the final temperature and the mass of contents of the calorimeter. ans 572.22g please ...
Tuesday, May 29, 2012 at 1:03am

physics
The length of a sonometer wire AB is 100cm where should the two bridges be placed from A to divide the wire in 3 segments whose fundamental frequencies are in the ratio of 1:2:6 options: 1.60cm,90cm 2.40cm,80cm
Tuesday, May 29, 2012 at 12:37am

Physics
An electric motor is rated to have a maximum power output of 0.72 hp. If this motor is being used to lift a crate of mass 188 kg, how fast (i.e., at what speed) can it lift the crate? Hint: Assume the only other force on the crate is the force of gravity.
Monday, May 28, 2012 at 11:53pm

Physics
You are heating water in a pot on the stove. Shortly before the water boils properly, bubbles of steam begin rising from the bottom of the pot but vanish before they reach the water’s surface. What happened to those bubbles?
Monday, May 28, 2012 at 10:38pm

Physics
At a restaurant, your glass of water contains 25% ice while your friend’s glass of water contains 75% ice. What can you say about their temperatures? Explain your answer.
Monday, May 28, 2012 at 10:38pm

physics
if the swinging pendulum (pirate ship) swings on an arc with a radius of 10 meters, how much time does it take to swing through 5 swings?
Monday, May 28, 2012 at 9:58pm

nuclear physics
An atom of Radium-228 transmutes to radon-222. Write the nuclear equation for this decay.... How ??
Monday, May 28, 2012 at 9:42pm

Physics(Please respond)
A golfer, standing on a fairway, hits a shot to a green that is elevated 5.33 m above where she is standing. If the ball leaves her club with a velocity of 48.0 m/s at an angle of 35.7 ° above the ground, find the time that the ball is in the air before it hits the green...
Monday, May 28, 2012 at 9:25pm

physics
To protect her new two-wheeler, Iroda Bike buys a length of chain. She finds that its linear density is 0.61 lb/ft. If she wants to keep its weight below 1.8 lb, what length of chain is she allowed?
Monday, May 28, 2012 at 9:18pm

physics ...plzzzz help...
1 ) If the mass of the Moon is 7.4 x 1022 kg and its radius is 1.74 x 106 m, compute the speed with which an object would have to be fired in order to sail away from it, completely overcoming the Moon’s gravity pull. 2 ) Show that if a satellite orbits very ...
Monday, May 28, 2012 at 9:05pm

Physics
A portable CD player requires 12 volts to operate. A transformer allows the device to be powered from a 120-volt outlet. If the primary has 500 turns, how many turns should the secondary have?
Monday, May 28, 2012 at 8:55pm

Physics(Please respond)
A golfer hits a shot to a green that is elevated 3.0 m above the point where the ball is struck. The ball leaves the club at a speed of 17.4 m/s at an angle of 35.0¢ª above the horizontal. It rises to its maximum height and then falls down to the green. Ignoring air ...
Monday, May 28, 2012 at 8:07pm

Physics
A convex lens forms a real image 6 times the size of the object. The distance between object and image is 33 cm. Find the focal length of the lens.
Monday, May 28, 2012 at 4:28pm

Physics(Please respond)
A 79.2-kg person stands on a scale in an elevator. What is the apparent weight when the elevator is (a) accelerating upward with an acceleration of 1.92 m/s2, (b) moving upward at a constant speed, and (c) accelerating downward with an acceleration of 1.89 m/s2 I was going to ...
Monday, May 28, 2012 at 4:23pm

Physics
A speaker at an open-air concert emits 600 of sound power, radiated equally in all directions. a)What is the intensity of the sound 7.00 from of the speaker? I =0.974 W/m^2 b) What sound intensity level would you experience there if you did not have any protection for your ...
Monday, May 28, 2012 at 3:36pm

physics
The ability to hear a "pin drop" is the sign of sensitive hearing. Suppose a 0.40 pin is dropped from a height of 30 , and that the pin emits sound for 1.4 when it lands. Assuming all of the mechanical energy of the pin is converted to sound energy, and that the ...
Monday, May 28, 2012 at 3:23pm

Science-Physics
One of the things that helped our understanding of radioactivity was the discovery of the electron in 1897. The 100th anniversary of this important discovery was celebrated widely in 1997. Explain why more people were aware of the 100th anniversary than of the original discovery.
Monday, May 28, 2012 at 2:17pm

Physics
Why does a transformer require alternating voltage?
Monday, May 28, 2012 at 11:04am

Physics
What is the basic difference between an electric generator and an electric motor?
Monday, May 28, 2012 at 10:45am

physics
a 20 ohm and 60 ohm resistors are connected in series to a DC generator. The voltage across the 20 resistor is 80 volts. The current through the 60 ohm resistor? A) 1.0A B) 5.0 A C) is about 1.3 A D)4.0 A E) cannot be calculated
Monday, May 28, 2012 at 10:32am

physics
an object is placed 10 cm from a concave spherical mirror whose radius of curvature is 12 cm. What is the distance of image a) 5cm b) 10 cm c)15cm d)20cm e)24cm
Monday, May 28, 2012 at 10:29am

physics
an electron moves with constant speed at right angles to a uniform magnetic flux, if the flux density were doubled, the force on the electron would be A) unaffected B) reduced to one month C) halved D) doubled E) quadrupled
Monday, May 28, 2012 at 10:25am

Physics
How much work is done against gravity in lifting a 6.5-kg weight through a distance of 21 cm?
Monday, May 28, 2012 at 10:17am

Physics
An engine expends 44.0 hp in moving a car along a level track at a speed of 13.9 m/s. How large is the total force acting on the car in the opposite direction of the motion of the car?
Monday, May 28, 2012 at 10:10am

physics
the angular frequency of a particle in a progressive wave in an elastic medium is 100.(3.14) rads^-1.and it is moving with a velocity of 200 ms^-1. the phase difference between two particles separated by a distance of 20cm is options: 1.31.4 rad 2.36 rad
Monday, May 28, 2012 at 10:09am

physics
if a stone at the end of a string is whirled in a circle, the inward pull on the stone A) is known as the centrifugal force B) is inversely proportional to the speed of the object C) is inversely proportional to the square of the speed D) is proportional to the speed E) is ...
Monday, May 28, 2012 at 9:58am

physics
a 60kg sprinter accelerates from rest at 2.5m/s east for 4s. what force is acting and what is his final speed?
Monday, May 28, 2012 at 6:47am

physics
a train starts from rest and accelerates uniformly at 100m/min^2 for 10 min.then it maintains a constant velocity for remaining 20 min.brakes are applied and train uniformly retards and comes to rest in next 5 min. a)the maximum velocity reached b)the retardation in last 5 min...
Monday, May 28, 2012 at 3:06am

physics
a train starts from rest and accelerates uniformly to achieve a velocity of 20m/sec in 10 sec.then train maintains this speed for next 200 sec.the breaks are then applied and train comes to rest in next 50 sec.calculate a)acceleration in first 10 sec. b)acceleration in last 50...
Monday, May 28, 2012 at 3:02am

physics
a cyclist start from rest and accelerate uniformly to achieve a velocity of 12m/sec in 5 sec.immediately he applied brake and come to rest in next 4 sec .calculate a)distance traveled during acceleration b)distance traveled during retardation. c)total displacement during whole...
Monday, May 28, 2012 at 2:56am

physics
a body moves with a uniform velocity of 2m/sec for 5 sec then velocity was uniformly accelerated and a velocity of 10m/sec was achieved in next 5 sec.then brakes were applied uniformly and body comes to rest in next 10 sec.calculate a)acceleration and retardation produced b)...
Monday, May 28, 2012 at 2:35am

physics
a car traveled at uniform velocity of 20m/sec for 5 sec the brakes are applied and car retards uniformly and come to rest in further 8 sec.find a)distance traveled in first five sec b)distance traveled after breaks are applied c)total displacement during this period and its ...
Monday, May 28, 2012 at 2:28am

physics
A 0.93 kg block is shot horizontally from a spring, as in the example above, and travels 0.539 m up a long a frictionless ramp before coming to rest and sliding back down. If the ramp makes an angle of 45.0° with respect to the horizontal, and the spring originally was ...
Monday, May 28, 2012 at 2:20am

Physics
A horse draws a sled horizontally across a snow-covered field. The coefficient of friction between the sled and the snow is 0.195, and the mass of the sled, including the load, is 202.4 kg. If the horse moves the sled at a constant speed of 1.857 m/s, what is the power needed ...
Sunday, May 27, 2012 at 11:05pm

Physics
A man throws a rock of mass m = 0.310 kg straight up into the air. In this process, his arm does a total amount of work Wnet = 105 J on the rock. Calculate the maximum distance, h, above the man's throwing hand that the rock will travel. Neglect air resistance.
Sunday, May 27, 2012 at 9:05pm

Physics
How do I use Kirchhoff's First Law -- the law of conservation of energy and the law of conservation of charge to prove the equivalent resistance formula. Rt = R1 + R2 + R3 ......
Sunday, May 27, 2012 at 7:24pm

Physics ( electrical )
If I have two objects charged, one on a insulated thread and one stationary, and I have one distances and an acceleration and I double the distance, I want to find out the acceleration, what formula do I use? ( the distance is halved and I need to find out the magnitude of the...
Sunday, May 27, 2012 at 7:18pm

Physics
You push your couch a distance of 3.6 m across the living room floor with a horizontal force of 198.0 N. The force of friction is 151.0 N. What is the work done by you, by the friction force, by gravity, and by the net force?
Sunday, May 27, 2012 at 6:50pm

Physics(thank you for the help)
A hot-air balloon is rising upward with a constant speed of 2.45 m/s. When the balloon is 3.22 m above the ground, the balloonist accidentally drops a compass over the side of the balloon. How much time elapses before the compass hits the ground? I know that average speed ...
Sunday, May 27, 2012 at 6:45pm

Physics
A car of mass m = 1450 kg is traveling at a speed of v0 = 79 km/h (21.9 m/s). Calculate the work that must be done by the brakes to completely stop the car in kJ
Sunday, May 27, 2012 at 6:43pm

Physics
An ideal spring has the spring constant k = 414 N/m. Calculate the distance this spring must be stretched from its equilibrium position for 22 J of work to be done in meters.
Sunday, May 27, 2012 at 6:37pm

Physics (electricity)
Which formula do you use for this problem ? two charged spheres, one suspended from a insulated thread and another held in place and unable to move. when one sphere S1 is brought to a distance of 2.00 x 10^-2m from S2, the acceleration of S1 is 3.00 x 10^10 m/s^2. If S1 is ...
Sunday, May 27, 2012 at 6:27pm

physics
An electron is accelerated in the uniform field E = 2.0 x 104 N/C between two parallel charged plates (Negative charged plate is on the left and positively charges plate is on the right). The separation of the plates is 1.5 cm. The electron is accelerated from rest near the ...
Sunday, May 27, 2012 at 6:04pm

physics
Imagine a car involved in a head-on crash. The driver, whose mass is m, is to be brought uniformly to rest within the passenger compartment by compressing an inflated air bag through a distance sc. Write an expression for the average force exerted on the bag in terms of m, vi...
Sunday, May 27, 2012 at 6:02pm

physics
Show that if a satellite orbits very near the surface of a planet with period T, the density (mass per unit volume) of the planet is p(rho)=3pi/(GT)^2
Sunday, May 27, 2012 at 6:02pm

Physics
Two objects are near a bar magnet. One is about 1 cm away, while the other is 6 cm away. Compare and contrast the magnetic force that affects each object. What do they want me to do?
Sunday, May 27, 2012 at 6:00pm

physics
If the mass of the Moon is 7.4 x 1022 kg and its radius is 1.74 x 106 m, compute the speed with which an object would have to be fired in order to sail away from it, completely overcoming the Moon’s gravity pull.
Sunday, May 27, 2012 at 5:59pm

Physics
The minimum frequency for the photoelectric effect of a zinc plate is 9.7 × 1014 Hz. What will be the kinetic energy of an ejected electron when a photon with a wavelength 200 nm (2.00 × 10 7 m) strikes it?
Sunday, May 27, 2012 at 5:58pm

physics
An 8.0 kg puck floating on an air table is travelling east at 15 cm/s. Coming the other way at 25 cm/s is a 2.0 kg puck on which is affixed a wad of bubble gum. The two slam head-on into each other and stick together. Find their velocity after the impact. How much kinetic ...
Sunday, May 27, 2012 at 5:58pm

physics
A +5.7 C and a -3.5 C charge are placed 25 cm apart. Where can a third charge be placed so that it experiences no net force? (Restrict your analysis to a linear one.)
Sunday, May 27, 2012 at 5:58pm

physics
Four 7.5 kg spheres are located at the corners of a square of side 0.60 m. Calculate the magnitude and direction of the gravitational force on one sphere due to the other three.
Sunday, May 27, 2012 at 5:57pm

physics
If a negative charge is initially at rest in an electric field, will it move towards a region of higher potential or lower potential? What about a positive charge? How does the potential energy of the charge change in each case?
Sunday, May 27, 2012 at 5:57pm

physics
Why do you lose weight when you enter a tunnel passing through a mountain tunnel or walk inside a skyscraper?
Sunday, May 27, 2012 at 5:56pm

physics
It is fairly easy to catch a 20 N steel weight dropped from a height of 0.25 m or so. But if you attempt to catch the weight while resting your hand flat on a table, you are likely to be injured. Explain.
Sunday, May 27, 2012 at 5:56pm

Physics
A baby elephant is stuck in a mud hole. To help pull it out, game keepers use a rope to apply a force FA, as part a of the drawing shows. By itself, however, force FA is insufficient. Therefore, two additional forces FB and FC are applied, as in part b of the drawing. Each of ...
Sunday, May 27, 2012 at 5:40pm

Physics ( electricity)
An electrom (qe = -1.6^-19 Coulomb) moves a distance of 0.170m in an 8.00 N/C electric field. Using appropriate formulas and a logical method, find the energy gained by the electrom. Whoa ... how do I do this???
Sunday, May 27, 2012 at 5:31pm

Honors Physics Question
Two objects are near a bar magnet. One is about 1 cm away, while the other is 6 cm away. Compare and contrast the magnetic force that affects each object. What do they want me to do?
Sunday, May 27, 2012 at 5:16pm

Physics(Please respond)
1) A cave explorer drops a stone from rest into a hole. The speed of sound is 343 m/s in air, and the sound of the stone striking the bottom is heard 1.33 s after the stone is dropped. How deep is the hole? I did 343 / 1.33. Is this correct? Physics(Please help) - drwls, ...
Sunday, May 27, 2012 at 4:50pm

Physics(thank you for the help)
1) A baby elephant is stuck in a mud hole. To help pull it out, game keepers use a rope to apply a force FA. By itself, however, force FA is insufficient. Therefore, two additional forces FB and FC are applied. Each of these additional forces has the same magnitude F. The ...
Sunday, May 27, 2012 at 4:45pm

PHYSICS
A coil with an area of 0.10 m2 is in a magnetic field of 0.20 T perpendicular to its area. It is flipped through 180° so that the part that was up is down. The flip takes 1.0 s. Estimate the average induced emf between the ends of the coil while it is being flipped. What ...
Sunday, May 27, 2012 at 4:12pm

PHYSICS
A straight 1.2 m length iron rod is moved at 10 m/s through the earth's magnetic field at a location where it has magnitude 1.0 × 105 T. What is the magnitude of the induced emf between one end of the wire and the other end? What formula do I use?
Sunday, May 27, 2012 at 4:10pm

physics
A wire loop has an area of 0.12 m2, and the magnetic field through it increases from 0 to 0.20 T in 0.30 s. What is the induced emf in the loop?
Sunday, May 27, 2012 at 3:53pm

physics
the equation of a transverse wave travel ling on a rope is given by y=10sin3.14(0.01x-2.00t)where y and x are in cm and t is in seconds.the maximum transverse speed of the particle in the rope is about options: 1. 62.8 cm/s 2. 75 cm/s
Sunday, May 27, 2012 at 1:50pm

PHYSICS PLEASE HELP
A particle travels counterclockwise around the origin at constant speed in a circular path that has a diameter of 2.50 m, going around twice per second. Point Q is on the path halfway between points P and R, which lie on the x axis and the y axis, respectively. State the ...
Sunday, May 27, 2012 at 1:41pm

Physics
1) A jetliner, traveling northward, is landing with a speed of 69.3 m/s. Once the jet touches down, it has 787 m of runway in which to reduce its speed to 13.6 m/s. Compute the average acceleration (magnitude and direction) of the plane during landing (take the direction of ...
Sunday, May 27, 2012 at 1:25pm

Physics
A plane is heading due south with an airspeed of 211 mph. A wind from a direction of 53 degrees is blowing at 17 mph. Find the bearing of the plane. (Note that bearings are measured from north, clockwise.) Round results to appropriate number of significant digits.
Sunday, May 27, 2012 at 1:21pm

Physics(Please help)
Determine the final speed assuming that the time elapsed since t=0 is 2.4s. Initial velocity is +12m/s acceleration is +3.4m/s^2 I tryed doing 12/2.4 and then 12/3.4 but both of these were incorrect? I am not sure what to do. Thank you.
Sunday, May 27, 2012 at 12:24pm

Physics(Please help)
1) The velocity of a diver just before hitting the water is -11.8 m/s, where the minus sign indicates that her motion is directly downward. What is her displacement during the last 1.06 s of the dive? I know that the formula for displacement is deltaX= x - x0. Would I do -11.8...
Sunday, May 27, 2012 at 12:14pm

physics
a particle of mass 5m moving with speed v, explodes and splits into two pieces with masses of 2m and 3m. The lighter piece continues to move in the original direction with speed v relative to the heavier piece. What is the speed of the lighter piece
Sunday, May 27, 2012 at 10:46am

physics
A cyclist is cycling at uniform velocity of 8m/sec for 8 sec then applies brakes and cycle come to rest in next 10 sec. calculate a)Distance traveled by uniform velocity. b)distance traveled by non-uniform velocity c)total distance traveled d)the average velocity in entire ...
Sunday, May 27, 2012 at 10:23am

physics
A student starts from rest from his house and accelerates uniformly at the rate of 2m/sec^2 for 30 sec then he apply break for 45 sec and come to rest at his school.how far is his school
Sunday, May 27, 2012 at 10:10am

physics please respond
A 16kg sled starts up a 28 degree incline with a speed of 2.4 m/s . The coefficient of kinetic friction is = 0.27. part a)How far up the incline does the sled travel? part b)What condition must you put on the coefficient of static friction if the sled is not to get stuck at ...
Sunday, May 27, 2012 at 3:58am

physics
A glass bulb with radius 15 cm is filled with water vapor at a temperature of 500 K. On the exterior of the bulb a spot with area 2.0 mm^2 is placed in contact with liquid nitrogen. This causes the temperature of the spot to drop well below 0◦C. When the gaseous water ...
Sunday, May 27, 2012 at 2:14am

Physics(Please help)
1) A cave explorer drops a stone from rest into a hole. The speed of sound is 343 m/s in air, and the sound of the stone striking the bottom is heard 1.33 s after the stone is dropped. How deep is the hole? I did 343 / 1.33. Is this correct?
Saturday, May 26, 2012 at 11:07pm

Physics(Please respond)
1) A penny is dropped from rest from the top of a very tall building. Assuming the height of the building is 407 m and ignoring air resistance, find the speed with which the penny strikes the ground. I am not sure how to start this. Thank you!
Saturday, May 26, 2012 at 11:04pm

Physics
A car is coasting to a stop. The total drag (frictional Forces) on the 200kg car equal 2000N. Initial velocity is 25 m/s 1. What is the acceleration of the car? 2. How far does it travel before comming to a stop?
Saturday, May 26, 2012 at 10:03pm

Physics
A thermoelectric-based power meter has a response time of 20 s and sensitivity (output voltage per unit incident power) of 90 mV/W. If the time response is reduced to 8 s by increasing the thermal conductance between the sensor element and heat sink, what will be the new ...
Saturday, May 26, 2012 at 1:48pm

physics
an elastic ball rebounces 70% when it is dropped from the height. if it is dropped from 60m what is the total distance travelled by the ball
Saturday, May 26, 2012 at 11:15am

Physics
1.(a) Explain the term time dilation. (b) Show that an interval of time observed in a moving frame of reference will be less than the same interval of the observed in a stationary frame of reference. 2. A rocket was found to be 150m when measured on earth. It then leaves and ...
Saturday, May 26, 2012 at 7:15am

Physics
1. For a particular piece of glass the refractive index for X- rays of wavelength 1.60 X 10^-6 less than unity. At what maximum angle, measured to the surface , must a beam of X-rays strike the glass to undergo total internal reflection? 2 An oil drop of thickness 2.5 x 10^-...
Saturday, May 26, 2012 at 6:46am

Physics
A uniform rod AB of length 2a and mass M is freely pivoted at A and is held with B vertically above A. It is then allowed to fall and when B is vertically below A it strikes a stationary particle , also of mass M,which sticks to the rod at B. The rod then turns through a ...
Saturday, May 26, 2012 at 6:14am

physics
12. A particle starts moving from rest with uniform acceleration. it travels a distance x in first 2 sec and a distance y in the next 2 sec .Then options: 1.y=x 2.y=3x
Saturday, May 26, 2012 at 5:58am

physics
a car moving with a speed of 50 km/hr can be spotted by breaks after at least 6m.If the same car is moving with a speed of 100km/hr the minimum stopping distance is? options: 1. 24m 2. 6m
Saturday, May 26, 2012 at 5:55am

physics
a car moving with constant acceleration covers a distance between two points 180m apart in 6 sec.its speed as it passes the second point in 45m/s. what is its acceleration and its speed at the first point? options: 1. -5 m/s^2;15m/s 2. 5 m/s^2;15m/s
Saturday, May 26, 2012 at 5:49am

physics
A particle moving with a constant acceleration describes in the last second of it's motion 9/25th of the whole distance.of it starts from rest ,how long is the particle is in motion and through what distance does it move if it describes 6cm in first second? options 1. 5s,...
Saturday, May 26, 2012 at 5:43am

physics
a bullet fired into a fixed target loses half of its velocity in penetrating 15cm.how much further will it penetrate before coming to rest? options: 1.5cm 2.15cm
Saturday, May 26, 2012 at 5:04am

physics
The ability to hear a "pin drop" is the sign of sensitive hearing. Suppose a 0.50 g pin is dropped from a height of 27 cm, and that the pin emits sound for 1.4 s when it lands. Assuming all of the mechanical energy of the pin is converted to sound energy, and that ...
Saturday, May 26, 2012 at 1:50am

Physics
After delivering his toys in the usual manner, Santa decides to have some fun and slide down an icy roof. The roof is 7 m in length and makes an angle of 41° with the horizontal. He starts from rest at the top of the roof and accelerates at the rate of 3.9 m/s2. The edge ...
Friday, May 25, 2012 at 10:12pm

Physics :)
The vector F is (12.0, −3.00) in rectangular notation. What is this same vector in polar notation? Express the angle as a positive number between 0° and 360°. I got 12.4, just can't get the angle.
Friday, May 25, 2012 at 6:17pm

Physics HELP!
A block of mass 3 kg slides along a horizontal surface while a 20-N force is applied to it at an angle of 25°. If needed, use g = 10 m/s2. For a coefficient of kinetic friction of 0.3 between the block and the surface, the frictional force acting on the block is most ...
Friday, May 25, 2012 at 5:39pm

PHYSICS!
Two blocks are connected by a massless cord and are being pulled to the right by an external force F. They are accelerating at 2 m/s2. If needed, use g = 10 m/s2. With a coefficient of kinetic friction of 0.3, the external force acting on the 8 kg block is most nearly A.55 N B...
Friday, May 25, 2012 at 5:38pm

Physics
Two cubic blocks are in contact, resting on a frictionless horizontal surface. The block on the left has a mass of mL = 6.70 kg, and the block on the right has a mass of mR = 18.4 kg. A force of magnitude 112 N is applied to the left face of the left block, toward the right ...
Friday, May 25, 2012 at 5:00pm

Physics(Please help)
1) two hot-air balloons are 48.2 m and 61.0 m above the ground. A person in the left balloon observes that the right balloon is 13.3° above the horizontal. What is the horizontal distance x between the two balloons? The left balloon is 48.2m and the right balloon is 61.0m...
Friday, May 25, 2012 at 4:56pm

physics please help
An astronaut stands at a position on the Moon such that Earth is directly overhead and releases a Moon rock that was in her hand. (c) What is the gravitational force exerted by the Earth on the same 2.7-kg rock resting on the surface of the Moon? answer in mN I keep ...
Friday, May 25, 2012 at 4:38pm

physics
A highway curve has a radius of 123 m. At what angle should the road be banked so that a car traveling at 26.5 m/s has no tendency to skid sideways on the road? [Hint: No tendency to skid means the frictional force is zero.] I can't get this one right either please someone...
Friday, May 25, 2012 at 4:25pm

physics
A car drives around a curve with radius 390 m at a speed of 32 m/s. The road is not banked. The mass of the car is 1200 kg. (a) What is the frictional force on the car? N c) Explain I really don't know how to solve this could someone please help me out on this. Thank you.
Friday, May 25, 2012 at 4:22pm

Physics
A particle travels counterclockwise around the origin at constant speed in a circular path that has a diameter of 2.50 m, going around twice per second. Point Q is on the path halfway between points P and R, which lie on the x axis and the y axis, respectively. State the ...
Friday, May 25, 2012 at 3:55pm

Physics
A solar sail is used to propel a spacecraft. It uses the pressure (force per unit area) of sunlight instead of wind. Assume the sail and its spacecraft have a mass of 245 kg. If the sail has an area of 62,500 m2 and achieves a velocity of 8.93 m/s in 12.0 hours starting from ...
Friday, May 25, 2012 at 3:28pm

Physics
1)A force vector points at an angle of 12.4 ° above the +x axis. It has a y component of +337 newtons (N). Find the magnitude and the x component of the force vector. For the x component I did 337cos(12.4)=329.13 N For magnitude I am not sure what to do.
Friday, May 25, 2012 at 3:00pm

Physics
If the juggler wants the balls to remain in the air for 1.4 seconds, (a) what should the vertical velocity be? (b) What should the horizontal velocity be? The distance between the juggler’s hands is 0.70 meters and the acceleration due to gravity is −9.80 m/s^2.
Friday, May 25, 2012 at 3:00pm

Physics(Please help)
1) A force vector has a magnitude of 579 newtons and points at an angle 43o of below the positive x axis. Find the x scalar component and the y scalar component of the vector? For the x component I did 579cos(43) = 423.45 N. Is this correct? For the y component I did 579sin(43...
Friday, May 25, 2012 at 2:44pm

Physics
Sam tosses a ball horizontally off a footbridge at 4.3 m/s. How much time passes after he releases it until its speed doubles? Can someone please explain the correct equation to use thoroughly and help me to find the correct answer?!
Friday, May 25, 2012 at 2:42pm

physics
A planet orbits a star once every 3.14x10^7 s in a nearly circular orbit of radius 1.51x10^11 m. (a) With respect to the star, determine the angular speed of the planet b) With respect to the star, determine the tangential speed of the planet. c) With respect to the star, ...
Friday, May 25, 2012 at 12:47pm

Physics(Please help)
A football is kicked with a speed of 18 m/s at an angle of 65° to the horizontal. How long is the football in the air? Neglect air resistance Would I use the equation y=y0 + voy t -1/2gt^2 ?
Friday, May 25, 2012 at 12:24pm

Physics(Please respond)
1) Which components remain constant throughout the motion? vx = x component of the velocity vy = y component of the velocity ax = x component of the acceleration ay = y component of the acceleration I know that ax and ay remain constant but I am not sure about vx and vy. Thank...
Friday, May 25, 2012 at 12:07pm

physics
A bicyclist moving at a constant speed takes 10.0 seconds to travel 500 meters down a path inclined 30.0° downward from the horizontal. What is the vertical velocity of this motion?Select one of the options below as your answer: A. 18.3 meters/second B. 43.3 meters/second ...
Friday, May 25, 2012 at 11:47am

physics-kinetic theory
A glass bulb with radius 15 cm is filled with water vapor at a temperature of 500 K. On the exterior of the bulb a spot with area 2.0 mm^2 is placed in contact with liquid nitrogen. This causes the temperature of the spot to drop well below 0◦C. When the gaseous water ...
Friday, May 25, 2012 at 7:32am

physics
a train moving at constant velocity of 54 k mph moves east wards for 30 min, then due to north with the same speed for 40 min. What is the average velocity of the train during the run?(in k mph)
Friday, May 25, 2012 at 4:38am

physics
a boy walks to his school at a distance of 6km with constant speed of 2.5 k mph and walks back with a constant sped of 4 k mph. His average speed of round trip expressed in k mph is?
Friday, May 25, 2012 at 4:33am

Physics
According to Boyle's law, the volume V of a gas at a constant temperature varies inversely with the pressure P. When the volume of a certain gas is 125 cubic meters, the pressure is 20 psi (pounds per square inch). If the volume of gas is increased to 400 cubic meters, the...
Friday, May 25, 2012 at 3:11am

physics
if a car covers 2/5th of the total distance with v1 speed and 3/5th distance with v2 then average speed is?
Friday, May 25, 2012 at 2:47am

physics- please respond
A 16kg sled starts up a 28 degree incline with a speed of 2.4m/s . The coefficient of kinetic friction is = 0.27. part a)How far up the incline does the sled travel? part b)What condition must you put on the coefficient of static friction if the sled is not to get stuck at the...
Friday, May 25, 2012 at 1:59am

physics
two uniform cylinders have different masses and different rotational inertias.they simultaneously start from rest at top of an inclined plane and rool without sliding down the plane.the cylinder that gets to the bottom first is?
Friday, May 25, 2012 at 1:44am

physics
for a body to be in equillibrium under the combined action of several forces
Friday, May 25, 2012 at 1:41am

physics
for an object in equillibrium the net torque acting on it vanishes only if each torque is calculated about?
Friday, May 25, 2012 at 1:38am

physics
the conditions that the net force and the net torque both vanish?
Friday, May 25, 2012 at 1:32am

chemistry/physics
A glass bulb with radius 15 cm is filled with water vapor at a temperature of 500 K. On the exterior of the bulb a spot with area 2.0 mm^2 is placed in contact with liquid nitrogen. This causes the temperature of the spot to drop well below 0◦C. When the gaseous water ...
Thursday, May 24, 2012 at 10:55pm

Physics
A sign weighing 10N hangs from two ropes. Each rope is 45 degrees from the horizontal. 1. What is the tension in each rope?
Thursday, May 24, 2012 at 10:20pm

physics
A car is coasting to a stop. The total drag (frictional Forces) on the 200kg car equal 2000N. 1. What is the acceleration of the car? 2. How far does it travel before comming to a stop?
Thursday, May 24, 2012 at 10:18pm

physics
current through a device is 0.30 A, and the resistance in the device is 40 Ù. How many 1.5 V batteries are required to run the device
Thursday, May 24, 2012 at 9:57pm

Physics
each resistor in the circuit shown is 5.0 Ù, and the battery is 12.0 V, what does the second ammeter (A2) read?
Thursday, May 24, 2012 at 9:52pm

physics..
what's the density of a box whose weight is 1648 newtons and whose volume is 2.8 cubic meters? Will it float in a liquid whose density is 600 kilograms per cubic meter?
Thursday, May 24, 2012 at 6:45pm

physics
if the pulleys are massless and frictionless and the rope is of negligible mass, and aristotle wanted to raise the 332 newton weight to a height of 6 meters. A-find the magnitude of force F he needed to pull on the rope to move the weight upward with a constant velocity. B-...
Thursday, May 24, 2012 at 6:24pm

physics
A weightless beam rests on two supports. The beam supports a weight of 120 newtons. What are the magnitudes of the forces on each end ( A & B) of the beam?
Thursday, May 24, 2012 at 6:21pm

physics
A female whose mass is 130 kilograms is standing on a scale in an elevator that has an initial downward velocity of 6 meters per second and is accelerating upward at 7 meters per second. What's the magnitude of the apparent weight indicated by the scale?
Thursday, May 24, 2012 at 6:19pm

physics
Trenton struggled as he lifted a 27kg mass vertically a distance of 9 meters in 4minutes with a constant velocity. A-how much work did he do? B-What was the average power comsumption in watts?
Thursday, May 24, 2012 at 6:17pm

physics
Forces of 1,5,3, and F newtons are applied to a weightless board that rests on a fulcrum. The board doesn't rotate-what's the magnitude of the force F?
Thursday, May 24, 2012 at 6:15pm

physics
a 1462 kilogram block was lifeted vertically at a constant velocity a distance of 0.08 x 10(to the 6th power) meters in 5minutes. A-how much work was done? B-what was the average power consumption in watts?
Thursday, May 24, 2012 at 6:06pm

physics
Three forces are applied to a box wrench. find the total torque about the bolt in newton-meters caused by these forces. Is the torque a positive torque or a negative torque?
Thursday, May 24, 2012 at 6:04pm

Physics
A magician pulls a tablecloth out from under some dishes. How far do the dishes move during the 0.25 it takes to pull out the tablecloth? The coefficient of kinetic friction between the cloth and the dishes is = 0.14.
Thursday, May 24, 2012 at 5:58pm

physics
The density of an unspecified material is 3.27 g/cm (cubed) . if the mass of a block of this material is 10.9kg, what is the volume of the block in cubic meters? A Wooden block is pulled to the right across a level surface at a constant velocity by a force of 47 Newtons, the ...
Thursday, May 24, 2012 at 5:03pm

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