Monday
September 1, 2014

# Homework Help: Science: Physics

physics
Which of the following was explained by the Bohr atom? 1. atomic spectra 2. the fact that most of the mass of an atom is in the nucleus 3. nuclear fission 4. the photoelectric effect
Wednesday, January 22, 2014 at 2:02pm

physics
How far would a car of 126 horse power have gone when it attains a speed of 70 km/hour going up the hill with 15 degrees incline. Total weight of the car is 1338 kg
Wednesday, January 22, 2014 at 11:31am

physics
A man walks 10km due south. The displacement of the man from the initial position is
Wednesday, January 22, 2014 at 6:37am

Physics
The goblins fists cut through the air and connects with the dwarfs face in an elastic collision. The goblins fists each weigh 2kg and the dwarfs head weighs 5kg. What is the kinetic energy imparted to the dwarfs face by the goblins fists if the goblins fists had an initial ...
Wednesday, January 22, 2014 at 2:50am

Physics
A lamp is 4m from wall. Calculate the focal length of a concave mirror which forms a five time magnified image of lamp on wall. How far from wall must the mirror be placed?
Wednesday, January 22, 2014 at 2:07am

Physics
an object 2.6 cm high is 24cm from concave mirror whose radius of curvature is 16cm. Determine the location of its image. the answer is 12cm in front of mirror. I want to know what to get this. What steps and which formulas are used? please help
Wednesday, January 22, 2014 at 1:26am

physics
A wave is described by the equation y = 3sin(5t - 3x + 2ð). What is the velocity of the wave?
Wednesday, January 22, 2014 at 1:08am

physics
Two ping pong balls each have a mass of 1.4 grams and carry a net charge of 0.450uC. one ball is held fixed. at what height should the second ball be placed directly above the fixed ball if it is to remain at rest there?
Wednesday, January 22, 2014 at 12:31am

physics(online)
Find the change in the force of gravity between two planets when distance between them is decreased by 12
Tuesday, January 21, 2014 at 10:20pm

Physics
A rock is dropped from rest. How fast is it going after it has been falling for 8.3 s?
Tuesday, January 21, 2014 at 9:31pm

physics
If instead, the swimmer makes 77.5 laps in the same pool in 1.5 h, determine the total distance the swimmer traveled, the swimmer's total displacement, the swimmer's average velocity, and the swimmer's average speed.
Tuesday, January 21, 2014 at 8:54pm

physics
If you have swam one lap in a swimming pool, that means you have swam from one end to the other and back. In 1.5 h, a swimmer makes exactly 77 laps in a swimming pool that is 27 m long. Determine the distance the swimmer traveled, the total displacement of the swimmer, the ...
Tuesday, January 21, 2014 at 8:53pm

Physics
A submarine is at a depth of 15.0 m under the ocean surface. The inside of the submarine is kept at atmospheric pressure. What is the net force being exerted on a circular window of the submarine that has a radius of 25 cm? The density of the ocean water is 1030 kg/m3. I know ...
Tuesday, January 21, 2014 at 8:52pm

physics
A rock is dropped from rest. How fast is it going after it has been falling for 8.3 s?
Tuesday, January 21, 2014 at 8:51pm

Physics
The velocity vector V1 has a magnitude of 4.0 m/s and is directed along the +x-axis. The velocity vector V2 has a magnitude of 3.0 m/s. The sum of the two is V3, so that V3 = V1+V2 A. The x-component of V3 can be 3.0 m/s B. The magnitude of V3 can be 8.0 m/s C. The magnitude ...
Tuesday, January 21, 2014 at 8:48pm

physics
A boy standing on top of a building throws a small ball from a height of H1 = 43.0 m. The ball leaves with a speed of 14.9 m/s, at an angle of 55.0 degrees from the horizontal, and lands on a building with a height of H2 = 14.0 m. Calculate for how long the ball is in the air...
Tuesday, January 21, 2014 at 8:45pm

physics
A fireman, 29.1 m away from a burning building, directs a stream of water from a ground level fire hose at an angle of 48.5° above the horizontal. If the speed is 51.6 m/s, at what height will the stream of water hit the building?
Tuesday, January 21, 2014 at 8:31pm

physics
A car starts at a position of x=6 km and has a speed of 6 mph. After 42 s the car has a speed of 60 mph. Determine the magnitude of the car's average acceleration during this time.
Tuesday, January 21, 2014 at 8:30pm

physics
an aluminium of mass 2.1 kg rests on a steel platform. A horizontal force of 15N is applied to block(a) given the coefficient of limiting friction is 0.61 will the block move? (b)if it moves what will be its acceleration?
Tuesday, January 21, 2014 at 5:46pm

physics
The blades of a ceiling fan have a radius of 0.340m and are rotating about a fixed axis with an intial angular velocity of +1.25rad/s2. When the switch on the fan is turned to a higher speed, the blades acire an angular acceleration of +2.55rad/s2. After 0.480s have elapsed ...
Tuesday, January 21, 2014 at 4:35pm

Physics
Attempting to stop on a slippery road, a car initially moving at 80 km/h skids at 30° to its initial motion, stopping in 3.9 s. Determine the average acceleration in m/s2 in coordinates with the x-axis in the direction of the original motion and the y- axis toward the side...
Tuesday, January 21, 2014 at 4:15pm

Physics
The figure shows a 7 kg block being pulled along a frictionless floor by a cord that applies a force of constant magnitude 20 N but with an angle θ(t) that varies with time. When angle θ = 29°, at what rate is the block's acceleration changing if (a)θ(t...
Tuesday, January 21, 2014 at 3:05pm

Physics
A 33.4 kg child, with a 3.05 kg backpack on his back, first stands on a sidewalk and then jumps up into the air. Find the force (positive up/negative down) on the sidewalk from the child when the child is (a) standing still and (b) in the air. Now find the net force (positive ...
Tuesday, January 21, 2014 at 2:55pm

Physics
Correct if i am wrong? Which of the following is a quantitative property of minerals? a. Cleavage b. Hardness **** c. Luster d. Streak Which of the following is NOT a characteristic of minerals? a. Occur in gaseous and liquid state b. Formed by inorganic processes c. Naturally...
Tuesday, January 21, 2014 at 12:47pm

Physics
If a current is flowing with a value of 5.9 A, how much electron charge passes any single point in 25 seconds? A) 1.9 x 1020 e
Tuesday, January 21, 2014 at 11:07am

physics
A 1500 kg car at rest rolls down a hill inclined at 10 degrees with the horizontal. A 400 N friction force opposes its motion on the inclined plane and a 600 N on the horizontal surface a) how fast will it be moving at point B b) how far from point C will it travel before ...
Tuesday, January 21, 2014 at 8:35am

physics
When a car is 100 meters from its starting position traveling at 60.0 m/s., it starts braking and comes to a stop 350 meters from its starting position in 8.3 s.
Tuesday, January 21, 2014 at 8:27am

physics
When a car is 100 meters from its starting position traveling at 60.0 m/s., it starts braking and comes to a stop 350 meters from its starting position in 8.3 s.
Tuesday, January 21, 2014 at 8:27am

physics
A body of mass 10kg in air and 4kg in water calculate the volume and its density
Tuesday, January 21, 2014 at 2:11am

physics
An object of volume 4 metercube is immersed in a liquid of density 1030 kilogramme per meter cubic meter calculate the upthrust of liquid of the object
Tuesday, January 21, 2014 at 12:40am

Physics
The speed of light in polythene is 1.99 x 108 m/s What is the index of refraction of polythene
Monday, January 20, 2014 at 10:29pm

physics
How much time does it take a pulse of light to travel through 180$${\rm {\rm m}}$$ of water?
Monday, January 20, 2014 at 9:11pm

Physics
A motorist travels at a constant speed of 37.0 m/s through a school zone, exceeding the posted speed limit. A policeman waits 7.0 s before giving chase at an acceleration of 3.2 m/s2. I have solved that it will take 36 seconds for the cop to catch up to the car. However, I am ...
Monday, January 20, 2014 at 9:00pm

Physics
an alpha particle of mass m= 6.6 x 10^-27 kg has a speed of .81c, where the speed of light is c= 3 x 10^8 m/s. The alpha particle collides with a gold nucleus and rebounds with the same speed in the opposite direction. If the collision lasted for t= 4 x 10^-7s, what is the ...
Monday, January 20, 2014 at 8:42pm

physics
A golfer hits a ball off a tee from an elevated platform 13m above the ground. if the golf ball leaves the tee at 85 m/s @ 15 degrees, find the flight time, the maximum height above the ground and the horizontal displacement of the golf ball.
Monday, January 20, 2014 at 8:35pm

physics
an electron of mass m has a speed of v. at what speed would the ration of the magnitudes of the relativistic and non relativistic momenta be equal to 2?
Monday, January 20, 2014 at 8:28pm

physics
A soccer ball is kicked off of the ground at 17 ft/sec @ 30 degrees. Determine the maximum height above the ground the ball reaches and how far downfield the ball lands.
Monday, January 20, 2014 at 8:05pm

physics
A boy runs off the edge of a 5 foot high wall @ 2.5 ft/sec. How long will he spend in the air? How far from the base of the wall will he land?
Monday, January 20, 2014 at 8:04pm

physics
A truck of mass 1.0 tonne moving at 4.0 m/s catches up and collides with a truck of mass 2.0 tonne moving at 3.0m/s in the same direction. The trucks become coupled together. Calculate their common velocity
Monday, January 20, 2014 at 7:34pm

physics
is this right?if 5.0m/s^2=6.0m/s-0/1.2s a=fn/m 5.0m/s=15.0N/3kg show that the 5.0m/s^2 acceleration can result from a net force of 15N exerted on a 3.ok cart
Monday, January 20, 2014 at 6:51pm

physics
a wheel with an angular velocity of 300. rev/min increases to 500. rev/min in 10.0 sec. what is the angular acceleration the wheel is traveling?
Monday, January 20, 2014 at 5:17pm

PHYSICS(HELP)
Eight charges (50μC each) are arranged on the corners of a cube side length 1 cm. What is the magnitude of the force on each charge in Newtons?
Monday, January 20, 2014 at 4:26pm

physics
An object of volume 4 metercube is immersed in a liquid of density 1030 kilogramme per meter cubic meter calculate the upthrust of liquid of the object
Monday, January 20, 2014 at 4:11pm

physics
An object of volume 4 metercube is immersed in a liquid of density 1030 kilogramme per meter cubic meter calculate the upthrust of liquid of the object
Monday, January 20, 2014 at 4:11pm

physics
An object of volume 4 metercube is immersed in a liquid of density 1030 kilogramme per meter cubic meter calculate the upthrust of liquid of the object
Monday, January 20, 2014 at 4:10pm

physics
An object of volume 4 metercube is immersed in a liquid of density 1030 kilogramme per meter cubic meter calculate the upthrust of liquid of the object
Monday, January 20, 2014 at 4:08pm

physics-forces
Kara (55kg) is standing next to her brother Ben (80kg) on a large piece on frictionless ice. Kara decided to push her brother with a force of 200N expecting him to slide across the ice while she remains standing in the middle of the ice rink laughing. a) Describe the motion ...
Monday, January 20, 2014 at 3:15pm

physics
Eight charges (50μC each) are arranged on the corners of a cube side length 1 cm. What is the magnitude of the force on each charge in Newtons?
Monday, January 20, 2014 at 2:28pm

Physics
Earlier I posted the tension question I knew how to get the equation of 50*9.81 = 2 (4360) sin A. I just don't know how to find (sin A) from here.
Monday, January 20, 2014 at 2:13pm

physics
Two charged spheres of charge q and mass m are each hanging from strings and are at equilibrium as shown below: Give an expression for tanθ in terms of ke (use "k" to write ke), q, m, g (gravity), and d (the distance between the spheres). tanθ=
Monday, January 20, 2014 at 1:29pm

physics
The combined mass of a man and a chair suspended at the midpoint of a rope of negligible mass is 50 kilograms. The rope is connected to a weight of 4360 newtons hanging from a massless frictionless pulley. Find the angle.
Monday, January 20, 2014 at 1:23pm

physics-forces
Kara (55kg) is standing next to her brother Ben (80kg) on a large piece on frictionless ice. Kara decided to push her brother with a force of 200N expecting him to slide across the ice while she remains standing in the middle of the ice rink laughing. a) Describe the motion ...
Monday, January 20, 2014 at 1:09pm

physics
Consider the freight train in Figure below. Suppose 17 boxcars pass by in a time of 10.7 s and each has a length of 15.3 m. (a) What is the frequency at which each boxcar passes? (b) What is the speed of the train?
Monday, January 20, 2014 at 1:00pm

physics
How much force is needed to accelerate a 125 kg block up a 35 degree include at 3.4 m/s2 if the coefficient of friction is 0.28?
Monday, January 20, 2014 at 12:11pm

physics
A 625 N crate, which is at rest on the floor, is pulled along the floor by a horizontal force of 85 N. The coefficient of friction is 0.11. How far will the crate go in 4.5 seconds?
Monday, January 20, 2014 at 12:09pm

physics
Two cables suspend a 500 N sign above the hallway. The left cable makes a 40 degree angle with the ceiling and the right cable makes a 50 degree angle with the ceiling. What is the tension in the left and right cables?
Monday, January 20, 2014 at 6:55am

physics
What is the apparent weight of a 55 kg person in an elevator accelerating downward at 2.2 m/s2?
Monday, January 20, 2014 at 6:33am

PHYSICS
A wave pulse on a string moves a distance of 8 m in 0.04 s. What would be the wavelength of the wave on the same string if its frequency is 200 Hz? (A) 0.4 m (B) 0.5 m (C) 0.8 m (D) 0.10 m.
Monday, January 20, 2014 at 6:11am

physics
Compute the force of attraction between a 25 kg. mass and a 45 kg. mass that are 9.6 meters apart from center to center.
Monday, January 20, 2014 at 1:12am

physics
A 50 foot see-saw has 4 kids sitting on it. A 62 lb. girl sits on the left end, with a 76 lb. girl sitting 2.5 feet in front of her. On the right side, a 96 lb. boy sits on the end and has another boy sitting 2.5 feet in front of him. How much does this other boy weigh?
Monday, January 20, 2014 at 1:09am

Physics
If an electron moves perpendicular to the same field with this speed,what is the radius of its circular orbit?
Monday, January 20, 2014 at 12:48am

Physics-forces
1. NASA launched a 550kg satellite into space. Its engines have a thrust of 8000N. a) What is the downward froce of gravity acting on the rocket at blast off? (is it 5390N?) b) What is the acceleration of the rocket at blast-off? (Hint: Fine Fnet first) 2. A planet has a mass ...
Monday, January 20, 2014 at 12:18am

Physics
An electron passes location <0.02m, 0.04m,−0.06m>, and 4 μs later is de- tected at location <0.02 m, 1.84 m,−0.86 m>. Find the average velocity of the elecron: ¯v = <vx, vy, vz> If the electron continues to travel at this av- erage ...
Sunday, January 19, 2014 at 9:07pm

physics
An electron passes location h0.02m, 0.04m,−0.06mi, and 4 μs later is de- tected at location h0.02 m, 1.84 m,−0.86 mi. Find the average velocity of the elecron: ¯v = <vx, vy, vz> If the electron continues to travel at this av- erage velocity, find ...
Sunday, January 19, 2014 at 8:48pm

Physics
Friction is usually the killer of efficiency. How does a ramp relate to friction?
Sunday, January 19, 2014 at 7:45pm

Physics
What is one advantage and one disadvantage of using a ramp? Explain in detail.
Sunday, January 19, 2014 at 7:44pm

Physics
What affect does changing the mass of an object on a ramp have on the efficiency of the ramp? Explain.
Sunday, January 19, 2014 at 7:43pm

Physics
Suppose that a binary star system consists of two stars of equal mass. They are observed to be separated by 380 million kilometers and take 9.0 Earth years to orbit about a point midway between them. What is the mass of each? ------------------------------- I've worked ...
Sunday, January 19, 2014 at 7:35pm

physics
A baseball has a mass of about 155 g. What is the magnitude of the momentum of a baseball thrown at a speed of 95 mph?(Note that you need to convert mass to kilograms and miles per hour to meters per second.) Answer in units of kg · m/s
Sunday, January 19, 2014 at 7:18pm

Physics
An ice skater skates 16.9 m southwest, then 33.8 m east, and finally 50.7 m in a direction 50.9◦ north of east. Find the magnitude of the displacement re- quired to bring the skater back to her starting point. Answer in units of m
Sunday, January 19, 2014 at 7:17pm

physics 2
two hundred fifty grams of water at 80 degree celsius is poured into a styrofoam cap of negligible heat capacity containing 180g of water at 10 degree celsius. after an additional 300 g of water to the cap, the mixture comes to the equilibrium temperature of 30 degree celsius...
Sunday, January 19, 2014 at 7:15pm

physics 2
if 120 g of hot water at 85 degree celsius is poured into an insulated cup containing 200 g of ice at 0 degree celsius. how many grams of liquid will there be when the system reaches thermal equilibrium?
Sunday, January 19, 2014 at 6:32pm

Physics
An explorer in the dense jungles of equatorial Africa leaves his hut. He takes 41 steps at an angle 45∘ north of east, then 81 steps at an angle 60∘ north of west, then 49 steps due south. Assume his steps all have equal length. Save him from becoming hopelessly ...
Sunday, January 19, 2014 at 4:37pm

physics
4.A steel rod is heated to 200 degrees Celcius and is then rigidly clamped at both ends and allowed to cool. Determine the temperature at which the rod will break if the tensile strength, coefficient of linear thermal expansion and youngs modulus of elasticity of the steel are...
Sunday, January 19, 2014 at 4:21pm

physics
3.The diameter of a pipe changes gradually from 150mm at point A, 6m above datum, to 75 mm at B, 3 m above the datum. The pressure at point A is 103KN/m^2 and the velocity of flow is 3.6m/s . Neglecting loses, determine the pressure at point B.
Sunday, January 19, 2014 at 4:21pm

physics
2.A solid iron cylinder with a diameter of 150mm a height of 1m and a density of 7860 kg/m^3 is suspended in fresh water (density of fresh water is 1000 kg/m^3) calculate the tension in the supporting cable when two thirds of the volume of the cylinder is submerged
Sunday, January 19, 2014 at 4:20pm

physics
Three forces are applied to an object, as indicated in the drawing. Force Farrowbold1 has a magnitude of 29.0 newtons (29.0 N) and is directed 30.0° to the left of the +y axis. Force Farrowbold2 has a magnitude of 18.9 N and points along the +x axis. What must be the ...
Sunday, January 19, 2014 at 4:15pm

Physics
If you have swam one lap in a swimming pool, that means you have swam from one end to the other and back. In 4.5 h, a swimmer makes exactly 69 laps in a swimming pool that is 35 m long. Determine the distance the swimmer traveled, the total displacement of the swimmer, the ...
Sunday, January 19, 2014 at 2:47pm

physics
A barefoot field-goal kicker imparts a speed of 39 m / s to a football initially at rest. If the football has a mass of 0 . 26 kg and the time of contact with the ball is 0 . 01 s, what is the force exerted by the ball on the kicker’s foot?
Sunday, January 19, 2014 at 2:43pm

Physics
A tuning fork creates sound wave with frequency of 170 hertz. If the speed of sound is 340 m/s, what is the wave length of the sound wave?
Sunday, January 19, 2014 at 2:38pm

Physics
A tuning fork creates sound wave with frequency of 170 hertz. If the speed of sound is 340 m/s, what is the wave length of the sound wave?
Sunday, January 19, 2014 at 2:30pm

physics- multiple choice
1. A transport truck pulls on a trailer with a force of 600N [E]. The trailer pulls on the transport truck with a force a) of zero b) of less than 600 N is the truck is slowing down c) equal to 600 N only if the truck is moving at constant velocity d) equal to 600 N no matter ...
Sunday, January 19, 2014 at 2:10pm

physics
A bucket of water has a weight of 40N.a man lifts the bucket by applying an upward force of 20N.at the same time a child pulls the bucket along the ground with a horizontal force of 10N...calculate the resultant force on the bucket
Sunday, January 19, 2014 at 12:20pm

physics
in a experiment to measure the speed of sound in glass, a pulse of sound is sent into a glass rod, 14 m in length. the reflected sound is detected after 5.6 ms (0.0056 s). calculate the speed of sound in glass.
Sunday, January 19, 2014 at 10:43am

physics
3 factors that we must always give when expressing a force vector quantity
Sunday, January 19, 2014 at 8:35am

physics
3 factors that we must always give when expressing a force vector quantity
Sunday, January 19, 2014 at 8:33am

physics
3 factors that we must always give when expressing a force vector quantity
Sunday, January 19, 2014 at 8:31am

Physics
The internal energy of a gas is 585 J. The gas is compressed adiabatically, and its volume decreases by 137 cm3. If the pressure applied on the gas during compression is 2.65 atm, what is the internal energy of the gas after the adiabatic compression?
Saturday, January 18, 2014 at 3:10pm

physics
A bucket ofwater has weight of 40N.A man lifts the bucket by applying an upward force of 20N,At the sawe time a child pulls the bucket along with a horizontal force of 10N,Calculate the resultant force on the bucket
Saturday, January 18, 2014 at 11:55am

physics
list three factors that we must always give when exprassing a force vector quantity
Saturday, January 18, 2014 at 11:51am

physics
A bucket of water has a weight of 40N.A man lifts the bucket up by applying an upward force of 20N .At the same time a child pulls the bucket along the ground with a horizontal force of 10N.draw a free-body diagram showing all the forces exerted on the bucket
Saturday, January 18, 2014 at 11:44am

college physics
The sound level when one child is talking in a room is 60.0 dB. What would be the sound level if all 20 children talk at the same time in the same room? Assume each child talks equally loudly.
Saturday, January 18, 2014 at 2:32am

physics
in a game a toy car slides down a slop if the top of the slope is 2 m higher than the foot of the slope how fast will the car be moving when it reaches the foot assume that all of its g.p.e is transformed to k.e (i'm 8th grade so simple answers pleas)
Saturday, January 18, 2014 at 2:10am

physics
A steel washer is suspended inside an empty shipping crate from a light string attached to the top of the crate. The crate slides down a long ramp that is inclined at an angle of 38∘ above the horizontal. The crate has mass 171kg . You are sitting inside the crate (with ...
Saturday, January 18, 2014 at 1:27am

1. An amusement park ride has a diameter of 16 meters and revolves at 15 rpm (revolutions per minute). How fast is a rider moving if she sits at the outermost part of the ride? A. 29.4 m/s B. 1.07 m/s <<<< C. 225 m/s D. 12.56 m/s E. 9.8 m/s 2. A police officer ...
Friday, January 17, 2014 at 8:55pm

Physics
How much (in Celsius degrees) is the temperature of 1.3 kg of alcohol raised by adding 4.1 kcal of heat? The following piece of information may come in handy: specific heat of alcohol is 0.58 kcal/kgC.
Friday, January 17, 2014 at 6:27pm

Physics
An aluminum calorimetry cup [mc = 0.6 kg, cc = 0.22 kcal/(kgC)] is filled with water [mw = 2.4 kg, cw = 1 kcal/(kgC)]. It is at a temperature of 30C. A sample of an unknown substance with mass mm = 2.34 kg, originally at a temperature of 210C, is added. After a while, the ...
Friday, January 17, 2014 at 6:25pm

Physics
A weightlifter manages to lift a 133 kg (that's 293 pounds, which sounds much more impressive) weight a distance of 1.4 m. How many kcal of heat energy is equivalent to this lift?
Friday, January 17, 2014 at 6:04pm

Physics
A gas cylinder of volume 26 liters contains an ideal gas at temperature 27 degrees C and pressure 1920 kPa. Some of the gas leaks until the pressure falls to 1500 kPa. How many moles of gas leaked, assuming that the temperature remains constant during this process?
Friday, January 17, 2014 at 5:37pm

Physics
A can of gasoline has a rectangular base with dimensions of 13.5 cm by 13 cm. If there are 3 liters of gasoline in the can, how much does the surface of the gasoline rise (in mm) in the can when the temperature is raised by 45C? The coefficient for volume expansion of gasoline...
Friday, January 17, 2014 at 5:35pm

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