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April 19, 2014

Homework Help: Science: Physics

Recent Homework Questions About Physics

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Physics
Consider the following distribution of objects: a 4.00-kg object with its center of gravity at (0, 0) m, a 1.20-kg object at (0, 3.00) m, and a 5.40-kg object at (2.00, 0) m. Where should a fourth object of mass 7.00 kg be placed so that the center of gravity of the four-...
Thursday, April 3, 2014 at 10:46pm

Physics
A uniform beam of length L = 8.00 m and weight 3.80 102 N is carried by two workers, Sam and Joe, as shown in the figure below. Determine the force that each person exerts on the beam.
Thursday, April 3, 2014 at 10:45pm

Physics
The blades of a motor rotate at a rate of 4401 rpm. When the motor is turned off, the blades slow to a new angular speed of 430 rpm in 4.93 seconds. What is the angular acceleration of the blades (in rads/sec^2)?
Thursday, April 3, 2014 at 10:32pm

physics
. A sonar signal is sent from a ship and the signal returns from the bottom 3.65 s later. How deep is the ocean if the speed of sound in water is 1,530 m/s?
Thursday, April 3, 2014 at 9:29pm

Physics
Va=219rev/20s * 6.28rad/rev=68.8 rad/s a=(V-Vo)/t = (68.8-0)/20=3.44 rad/s^2. Circumference=pi*2r = 6.28 * 68=427 cm= 4.27 m. d = 219revs * 4.27m/rev = 935.2 m.
Thursday, April 3, 2014 at 8:35pm

Physics -- check answers please
1. My answer is zero, because the car did not move backwards. However, you should get a 2nd opinion. 2. KE = 0.5*m*V^2 = 40 Joules KE = 0.5*5*V^2 = 40 2.5V^2 = 40 V^2 = 16 V = 4 m/s. 3c. 4a. PE + KE = Constant 5. I don't know what you mean by 4 100 J If you mean 400 J. the...
Thursday, April 3, 2014 at 8:08pm

Physics
Speed = 2*pi*r/t = 2*3.142*1.50E11/3.16E7 = 29,829m/s
Thursday, April 3, 2014 at 8:00pm

Physics 141
The drawing shows a person (weight W = 586 N, L1 = 0.837 m, L2 = 0.397 m) doing push-ups. Find the normal force exerted by the floor on each hand and each foot, assuming that the person holds this position. force on each hand N force on each foot N
Thursday, April 3, 2014 at 7:51pm

physics!
Ok, so after struggling through the above explanation I decided to repost a (imho) better worded, generalized explanation: Firstly let me define my variables: Fb=force of BOTH back wheels on the ground=2F(1backwheel) Ff=force of BOTH front wheels on the ground=2F(1frontwheel) ...
Thursday, April 3, 2014 at 7:48pm

Physics 141
The drawing shows a bicycle wheel resting against a small step whose height is h = 0.125 m. The weight and radius of the wheel are W = 23.1 N and r = 0.330 m, respectively. A horizontal force vector F is applied to the axle of the wheel. As the magnitude of vector F increases...
Thursday, April 3, 2014 at 7:36pm

physics
How you find the oscillation period of a mass if not given the mass, or spring constant? A mass is attached to a vertical spring, which then goes into oscillation. At the high point of the oscillation, the spring is in the original unstretched equilibrium position it had ...
Thursday, April 3, 2014 at 7:29pm

PHYSICS
A rock is thrown vertically upward with a speed of 14.0m/s from the roof of a building that is 70.0m above the ground. Assume free fall. In how many seconds after being thrown does the rock strike the ground? What is the speed of the rock just before it strikes the ground?
Thursday, April 3, 2014 at 7:25pm

Physics
Alice is going on a picnic and is aware that it will be easier to carry the picnic basket if it balances at the center where the handle is attached. She has placed a 1.55-kg container of potato salad at one end and a 0.675-kg package of hot dogs at the other end of a 52.0-cm ...
Thursday, April 3, 2014 at 7:12pm

physics (clear answer)
Multiple-Concept Example 10 provides one model for solving this type of problem. Two wheels have the same mass and radius of 5.0 kg and 0.47 m, respectively. One has (a) the shape of a hoop and the other (b) the shape of a solid disk. The wheels start from rest and have a ...
Thursday, April 3, 2014 at 6:34pm

physics (clear answer)
The wheels, axle, and handles of a wheelbarrow weigh W = 56.2 N. The load chamber and its contents weigh WL = 584 N. The drawing shows these two forces in two different wheelbarrow designs. To support the wheelbarrow in equilibrium, the man's hands apply a force to the ...
Thursday, April 3, 2014 at 6:33pm

physics (clear answer)
Two children hang by their hands from the same tree branch. The branch is straight, and grows out from the tree trunk at an angle of 26.1° above the horizontal. One child, with a mass of 43.6 kg, is hanging 1.31 m along the branch from the tree trunk. The other child, with...
Thursday, April 3, 2014 at 6:21pm

physics
A crate with a mass of 80 kg glides through a space station with a speed of 2.5 m/s. An astronaut speeds it up by pushing on it from behind with a force of 210 N, continually pushing with this force through a distance of 8 m. The astronaut moves around to the front of the ...
Thursday, April 3, 2014 at 6:14pm

Physics
A particular garden hose has an inside diameter of 15/16 in. The nozzle opening has a diameter of 5/16 in. When the flow speed of the water in the hose is 0.58 m/s, what is the flow speed through the nozzle?
Thursday, April 3, 2014 at 5:18pm

Physics
A spherical hydrogen-filled balloon is used to lift a load of 5950 N (in addition to the weight of the hydrogen). Suppose the density of the air is 1.18 kg/m3. Find the minimum necessary radius for the balloon
Thursday, April 3, 2014 at 5:18pm

Physics
A 4.8 kg container of water sits on a scale A. A cube of aluminum with sides of length 11.0 cm is suspended from a spring scale B so that half of the block is submerged in the water. What is the reading (in N) on spring scale B The continual question is What is the reading (...
Thursday, April 3, 2014 at 5:16pm

physics
How you find the oscillation period of a mass if not given the mass, or spring constant? A mass is attached to a vertical spring, which then goes into oscillation. At the high point of the oscillation, the spring is in the original unstretched equilibrium position it had ...
Thursday, April 3, 2014 at 5:00pm

Physics
F=P*A A= Pi*r^2 A=Pi*(25/2)^2 A=0.04909 cm^2 Pgauge=Pabs- 1 atm p abs =P gauge+1 P abs= 4 atm F= (0.04909 cm^2 * (1m^2)/(100cm)^2)*(4 atm*1.013*10^5 N/m^2) F=1.99 N
Thursday, April 3, 2014 at 4:22pm

Physics
Wrong answer.
Thursday, April 3, 2014 at 3:29pm

Physics
500m
Thursday, April 3, 2014 at 3:26pm

Physics
500m
Thursday, April 3, 2014 at 3:26pm

Physics
Your teacher is incredibly easy energy=plancksconstant*frequency
Thursday, April 3, 2014 at 3:23pm

physics
I am not doing your homework. I will happily critique your thinking or work.
Thursday, April 3, 2014 at 3:21pm

physics
Period=2PIsqrt(l/g)
Thursday, April 3, 2014 at 3:20pm

Physics
distance=tangential velocity*time tangential velocity=2PI*radius*angular speed time=44min*60sec/min
Thursday, April 3, 2014 at 3:19pm

physics
A particular person’s lower leg is 59 cm long and has a mass of 8.0 kg. If allowed to swing freely, with what time period would the leg swing? (Treat the leg as a simple pendulum with length equal to half the leg length and all the leg’s mass concentrated at this ...
Thursday, April 3, 2014 at 3:17pm

Physics
Here's a stationary bike. If you pedal such that the front wheel rotates at 6.7 rad/s, and that wheel's radius is half a meter, how far would you have gone in 44 minutes, if the bike where a non-stationary bike? (Assume a constant speed of rotation)
Thursday, April 3, 2014 at 3:02pm

physics
Calculate the water pressure at the bottom of the 50-m {\rm m}-high water tower shown in the photo. Express your answer to two significant figures and include the appropriate units
Thursday, April 3, 2014 at 2:09pm

physics
Calculate the water pressure at the base of the Hoover Dam. The depth of water behind the dam is 220m m . Express your answer to two significant figures and include the appropriate units
Thursday, April 3, 2014 at 2:09pm

physics
The top floor of a building is 40m m above the basement. Calculate how much greater the water pressure is in the basement than on the top floor. Express your answer to two significant figures and include the appropriate units.
Thursday, April 3, 2014 at 2:08pm

physics
Calculate the average force per nail when Sarah (following figure), who weighs 130 pounds, lies on a bed of nails and is supported by 600 nails. (Figure 1) Express your answer using two significant figures.
Thursday, April 3, 2014 at 2:08pm

physics
A dike in Holland springs a leak through a hole of area 0.60cm 2 cm^2 at a depth of 1.4m m below the water surface. How much force must a boy apply to the hole with his thumb to stop the leak? Express your answer to two significant figures and include the appropriate units.
Thursday, April 3, 2014 at 2:07pm

physics
Find its density. Express your answer to two significant figures and include the appropriate units How does this compare with the density of water? Express your answer using two significant figures.
Thursday, April 3, 2014 at 2:06pm

physics
In the sketch, the small hydraulic piston has a diameter of 2.5cm cm . The large piston has a diameter of 6.4cm cm . For each newton of force applied to the small piston, how many newtons of force are exerted by the large piston? Express your answer using two significant ...
Thursday, April 3, 2014 at 2:06pm

physics.
Rank the following from most to least for the percentage of its volume above the water line: A. Basketball floating in saltwater B. Basketball floating in glycerin C. Basketball floating in gasoline
Thursday, April 3, 2014 at 2:05pm

Physics
What is the energy of a single photon with a frequency of 7 x 10^8 Hz. (hint Planck's constant = 6.626 x 10^-34) To type an answer in scientific notation, use 'e'. For example, Planck's constant would be typed in as 6.626e-34.
Thursday, April 3, 2014 at 1:12pm

Physics
A baby whale gets lost from his mother while swimming through a large underwater canyon. Frantically the baby whale yells for his mommy. 1.5 seconds later, the whale hears his yell's ECHO from the canyon wall. How far is it to the canyon wall? The speed of sound in water ...
Thursday, April 3, 2014 at 1:04pm

PHYSICS!!!
A boat moves at 7.00m/s relative to the water. (You can neglect relativity at these slow speeds.) The boat travels 100 m downstream and then 100 m upstream, returning to its original point. Find the time for the round trip
Thursday, April 3, 2014 at 10:49am

physics
A jogger with a mass of 66.0 kg reaches the top of a staircase in 44.0 s. If the distance from the bottom to the top of the staircase is 14.0 m, how much power will the jogger create in climbing the stairs?
Thursday, April 3, 2014 at 10:40am

Physics
A star rotates twice in 24 hours. It then goes supernova, meaning it explodes and its radius gets a lot larger, about 4 times larger. Additionally, the explosion sends most of the mass to the edge of the sphere, making it resemble a spherical shell instead of a solid sphere. ...
Thursday, April 3, 2014 at 9:14am

Physics
6kcal
Thursday, April 3, 2014 at 6:34am

Physics Help
A graph of wavelength vs. 1/frequency should be a straight line. What are it's slope and y-intercept? I'm not given any graphs or numbers, just this question. And I know that Velocity = frequency x wavelength And that slope is found by rise/run and m= y2-y1/x2-x1 ...
Thursday, April 3, 2014 at 3:23am

physics
Does changing the angle of an incline that you are rolling a ball down change any of these paramaters? Final velocity of the ball, work, initial potential energy, and final kinetic energy?
Thursday, April 3, 2014 at 2:43am

Physics
How far vertically does it move? What is the final mechanical energy (the sum of U and the two types of K)? What, then, was the initial mechanical energy? What is the rotational inertia (see Table 10-2)? How is the angular speed related to the com speed?
Thursday, April 3, 2014 at 1:50am

PHYSICS!!
f=c/418E-9 c/418E-9 * Lambda=c*.75 lambda=4.18E-9 * .75
Thursday, April 3, 2014 at 1:45am

PHYSICS!!
Light travels at about 0.75c in water. A)What's the wavelength in water of light whose wavelength in vacuum is 418nm
Thursday, April 3, 2014 at 12:47am

Physics
A uniform beam of length L = 8.00 m and weight 3.80 102 N is carried by two workers, Sam and Joe, as shown in the figure below. Determine the force that each person exerts on the beam.
Wednesday, April 2, 2014 at 10:26pm

Physics
Consider the following distribution of objects: a 4.00-kg object with its center of gravity at (0, 0) m, a 1.20-kg object at (0, 3.00) m, and a 5.40-kg object at (2.00, 0) m. Where should a fourth object of mass 7.00 kg be placed so that the center of gravity of the four-...
Wednesday, April 2, 2014 at 10:26pm

physics
a = (Fap-Fk)/m = (160-24)/20 = 6.8 m/s^2
Wednesday, April 2, 2014 at 10:18pm

physics
V = Vo + a*t = 30 m/s 0 + a*4 = 30 a = 30/4 = 7.5 m/s^2.
Wednesday, April 2, 2014 at 9:59pm

physics
I once was given a metal whiskey flask for being in my cousin’s wedding. When it got dented, I put in 1 gram of H2O (initially 21°C, just like the air filling the rest of the flask) and heated it up to boil the water. It popped the dent out. Assume the flask had a ...
Wednesday, April 2, 2014 at 9:35pm

physics
P is to the left
Wednesday, April 2, 2014 at 8:17pm

physics
The Earth has a radius of about 6.38 ´ 103 kilometers at the equator and rotates 360° every 24 hours. The angular displacement of a person standing at the equator for 8.0 hours is:
Wednesday, April 2, 2014 at 7:54pm

physics
what are you trying to find here?
Wednesday, April 2, 2014 at 7:29pm

physics
What linear speed must a 0.0508-kg hula hoop have if its total kinetic energy is to be 0.164 J? Assume the hoop rolls on the ground without slipping.
Wednesday, April 2, 2014 at 6:21pm

physics
A billiard ball of mass m = 0.250 kg hits the cushion of a billiard table at an angle of θ1 = 70.0° at a speed of v1 = 2.50 m/s. It bounces off at an angle of θ2 = 63.0° and a speed of v2 = 2.10 m/s.
Wednesday, April 2, 2014 at 5:50pm

physics
A wheel, starting from rest, has a constant angular acceleration of 1.8 rad/s^2. In a 3.1-s interval, it turns through an angle of 142 rad. How long has the wheel been in motion at the start of this 3.1-s interval?
Wednesday, April 2, 2014 at 5:39pm

physics
A submarine is stranded on the bottom of the ocean with its hatch 25.0 m below the surface. Calculate the force needed to open the hatch from the inside, given it is circular and 0.450 m in diameter. Air pressure inside the submarine is 1.00 atm.
Wednesday, April 2, 2014 at 5:26pm

Physics
Consider the following distribution of objects: a 4.00-kg object with its center of gravity at (0, 0) m, a 1.20-kg object at (0, 3.00) m, and a 5.40-kg object at (2.00, 0) m. Where should a fourth object of mass 7.00 kg be placed so that the center of gravity of the four-...
Wednesday, April 2, 2014 at 5:10pm

Physics
A uniform beam of length L = 8.00 m and weight 3.80 102 N is carried by two workers, Sam and Joe, as shown in the figure below. Determine the force that each person exerts on the beam.
Wednesday, April 2, 2014 at 5:10pm

Physics
It shows a ball going along a frictionless track. How do you find the kinetic energy at position B on the track if position B is 15 above the ground and position A is 20 meters above the ground? The weight of the ball is .020 kg
Wednesday, April 2, 2014 at 4:52pm

physics
pressure cookers have been around for more than 30 years, although their use has stongly declined in recent years.how much force must the latches holding the lid onto pressure cooker be able to withstand if the circular lid is 25 cm in diameter and the gauge pressure inside is...
Wednesday, April 2, 2014 at 4:44pm

physics college level
A 2.0-kg block is projected up a frictionless inclined plane with a speed of 10 m/s. The angle of inclination is 30o . The block goes a distance of _____ up the plane before stopping. Assume g = 10 m/s2
Wednesday, April 2, 2014 at 4:27pm

Physics
v = Vo + at s = Vo*t + 1/2 at^2 12 = Vo + 10a a = (12-Vo)/10 100 = Vo*10 + (12-Vo)/20 * 100 100 = 10Vo + 5(12-Vo) 100 = 5Vo + 60 Vo = 8
Wednesday, April 2, 2014 at 4:11pm

Physics
In a relay race the second runner does not start from rest. it covers 100 m in 10 sec, finishing with maximum velocity of 12 m/sec, assuming the constant acceleration, determine his initial velocity. ??
Wednesday, April 2, 2014 at 4:09pm

Physics
A satellite is given a boost of 540 MJ of energy to move it from its initial orbit at an altitude of 150 km to a higher altitude orbit. If the satellite has a mass of 1.16 ✕ 10^3 kg, what is the new altitude it reaches? Take the mass of the Earth to be 5.97 x 10^24 kg ...
Wednesday, April 2, 2014 at 3:59pm

Physics
In a relay race the second runner does not start from rest. it covers 100 m in 10 sec, finishing with maximum velocity of 12 m/sec, assuming the constant acceleration, determine his initial velocity. ??
Wednesday, April 2, 2014 at 3:10pm

Physics
The flywheel of a steam engine runs with a constant angular speed of 112 rev/ min . When steam is shut off, the friction of the bearings and the air brings the wheel to rest in 2.2 h. What is the magnitude of the constant angular acceleration of the wheel in rev/min^2? Do not ...
Wednesday, April 2, 2014 at 1:42pm

Physics
A cyclist starts from rest and pedals such that the wheels of his bike have a constant angular acceleration. After 20.0 s, the wheels have made 219 rev. What is the angular acceleration of the wheels? What is the angular velocity of the wheels after 20.0 s? If the radius of ...
Wednesday, April 2, 2014 at 1:35pm

Physics -- check answers please
1. A boy pushes a car to slow it down while the car is rolling horizontally down the road. If the boy pushes backwards on the car with 10N of force as the car rolls forward 3.0m, the amount of work done by the boy is: a)-30 b)0 c)3.3 J d)30 N•m e)300J my answer: a 2. what...
Wednesday, April 2, 2014 at 12:22pm

Physics
I think I got it. c) ω0 t + (0.5*α*t^2) d) 911.3 Can you just double check this?
Wednesday, April 2, 2014 at 11:14am

Physics
I already figured out the answers to some but I need help with two more. 1) A disk with an initial angular velocity ω0 = 4.5 rad/s experiences a constant angular acceleration of α = 7.5 rad/s2 for time t = 15 s. Please answer the following questions. ω0 = 4.5 ...
Wednesday, April 2, 2014 at 11:06am

Equation help
A physics student stands at the top of a hill that has an elevation of 56 meters. he throws a rock and it goes up into the air and then falls back past him and lands on the ground below. The path of the rock can be modeled by the equation y=0.04x^2+1.3x+56 where x is the ...
Wednesday, April 2, 2014 at 10:31am

physics
density=mass/volume=70/(1.8)^3 g/cm^3
Wednesday, April 2, 2014 at 9:00am

physics
The mass of an iron cube having an edge length 1.8 cm is 70 g. Find itd density.
Wednesday, April 2, 2014 at 8:22am

Physics
dfasdfas
Wednesday, April 2, 2014 at 6:16am

physics
not of the mass itself, but about some other point. For example for a point mass hanging from a nail on a string it is m L^2 about the attachment point at the ceiling where L is the length of the string.
Wednesday, April 2, 2014 at 12:48am

Physics
original east momentum = 2115*10.61 final east momentum = (2115+3169)*5.03cos32.4 22440 = 5284 * 4.25 v = 22440 v v =1 m/s
Wednesday, April 2, 2014 at 12:45am

Physics
A 2115 kg car moving east at 10.61 m/s col- lides with a 3169 kg car moving north. The cars stick together and move as a unit after the collision, at an angle of 32.4◦ north of east and at a speed of 5.03 m/s. What was the speed of the 3169 kg car before the collision?
Tuesday, April 1, 2014 at 11:46pm

physics
Is there a way to calculate the moment of inertia of a hanging mass (3.1 kg) without length & width dimensions?
Tuesday, April 1, 2014 at 11:26pm

Physics
A uniform beam of length L = 8.00 m and weight 3.80 102 N is carried by two workers, Sam and Joe, as shown in the figure below. Determine the force that each person exerts on the beam.
Tuesday, April 1, 2014 at 10:39pm

Physics
Consider the following distribution of objects: a 4.00-kg object with its center of gravity at (0, 0) m, a 1.20-kg object at (0, 3.00) m, and a 5.40-kg object at (2.00, 0) m. Where should a fourth object of mass 7.00 kg be placed so that the center of gravity of the four-...
Tuesday, April 1, 2014 at 10:39pm

Physics-Gravitational Potential Energy
A satellite is given a boost of 540 MJ of energy to move it from its initial orbit at an altitude of 150 km to a higher altitude orbit. If the satellite has a mass of 1.16 ✕ 103 kg, what is the new altitude it reaches? Take the mass of the Earth to be 5.97 x 10^24 kg ...
Tuesday, April 1, 2014 at 10:06pm

Physics
When a small object is launched from the surface of a fictitious planet with a speed of 52.0 m/s, its final speed when it is very far away from the planet is 32.0 m/s. Use this information to determine the escape speed of the planet.
Tuesday, April 1, 2014 at 10:04pm

Physics
sorry, my diagram is not showing properly .. it is a pulley with mass one hanging from the left side and mass two hanging from the right side
Tuesday, April 1, 2014 at 10:03pm

Physics
For the system of two crates and a pulley in the figure below, what fraction of the total kinetic energy resides in the pulley? (Assume m1 = 14 kg, m2 = 10 kg and mpulley = 5 kg.) (( o )) | | | | [m1] | [m2]
Tuesday, April 1, 2014 at 9:58pm

Physics
wewrqwe
Tuesday, April 1, 2014 at 9:46pm

Physics
A 920kg car is 65m from a concrete barrier, travelling at 125km/h, when the driver notices and slams on the breaks. The frictional force acting on the car is 8500 N. Is ther driver able to stop the car before hitting the barrier.
Tuesday, April 1, 2014 at 9:39pm

physics
Assume all angles to be exact. The critical angle between two materials is 45∘. If the angle of incidence is 35∘, what is the angle of refraction? (Consider that light can travel to the interface from either material.)
Tuesday, April 1, 2014 at 9:35pm

physics
An outdoor circular fish pond has a diameter of 4.00 m and a uniform full depth of 1.60 m . A fish halfway down in the pond and 0.70 m from the near side can just see the full height of a 1.80 m tall person. How far away from the edge of the pond is the person?
Tuesday, April 1, 2014 at 9:34pm

Physics
9. Question : Cheryl runs a race on a circular 400.0 m track. She starts running east at the starting line and stops 20.0 m west of the starting line. Her time is 8.0 × 101 s. What is her average speed? 4.8 m/s 2.1 × 10-1 m/s -2.5 × 10-1 m/s 5.0 × 101 ...
Tuesday, April 1, 2014 at 9:25pm

physics
Madison pushes with a 160-N horizontal force on a 20-kg crate of coffee resting on a warehouse floor.the floor of friction force of 24N.show that the box accelerates is 4m/s²
Tuesday, April 1, 2014 at 9:22pm

physics
show that the acceleration is 7.5 m/s² for a ball that starts from rest and rolls down a ramp and gains a speed of 30 m/s in 4s
Tuesday, April 1, 2014 at 8:42pm

physics
tt
Tuesday, April 1, 2014 at 8:15pm

Physics
The impulse given to a ball with mass of 4 kg is 16 N s. If the ball starts from rest, what is its final velocity?
Tuesday, April 1, 2014 at 7:50pm

physics
oops, forgot to square my x
Tuesday, April 1, 2014 at 6:02pm

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