Friday

March 27, 2015

March 27, 2015

**Recent Homework Questions About Physics**

Post a New Question | Current Questions

**Physics **

You are given a four-wheeled cart of mass 11 kg, where the distance between a wheel and its nearest neighbors is 2.1 m. Suppose we load this cart with a crate of mass 109 kg, where the crate's center of mass is located in the back-middle of the cart, 0.525 m from its ...
*Sunday, April 6, 2014 at 8:43pm*

**physics**

A series RLC circuit is made with a C=100pF capacitor, an L=100μH inductor, and an R=30Ω resistor. The circuit is driven at 5×106rad/s with a 1V amplitude. What is the current oscillation amplitude in amps
*Sunday, April 6, 2014 at 5:04pm*

**Physics**

In the device a 50g mass is hung from a pulley and released. A disk is placed on the platform. The platform has a radius of 5cm. The disk and platform go from rest to an angular velocity of 8.5rad/s in 2.5 seconds. What is the moment of inertia of the disk? What is its mass? ...
*Sunday, April 6, 2014 at 4:56pm*

**Physics**

Boxcar A, with a mass of 1500 kg, is travelling at 25 m/s to the east. Boxcar B has a mass of 2000 kg, and is initially at rest. The boxcars collide inelastically and move together after they get stuck. What is their combined velocity?
*Sunday, April 6, 2014 at 3:41pm*

**Physics**

A bullet is fired horizontally with a speed of 100 m/s aiming at a target 20m away. It misses the target by??
*Sunday, April 6, 2014 at 2:58pm*

**cape1 physics**

a hammer is often used to force a nail into wood.the faster the hammer moves,the deeper the nail moves into the wood.
*Sunday, April 6, 2014 at 12:56pm*

**Math/Physics**

Problem Question: Rashad started The 780km drive from Sault st. Marie to Ottawa at 09:00. His average speed was 100km/h. Two hours later Tyson left Ottawa for Sault St. Marie. He drove at 80km/h on the same highway. How far from Ottawa, and what time of day did they meet?
*Sunday, April 6, 2014 at 12:26pm*

**physics**

A lightning bolt may carry a current of 1.00 ✕ 104 A for a short time interval. What is the resulting magnetic field 134 m from the bolt? Assume that the bolt extends far above and below the point of observation.
*Sunday, April 6, 2014 at 12:14pm*

**physics**

A series RLC circuit is made with a C=100pF capacitor, an L=100μH inductor, and an R=30Ω resistor. The circuit is driven at 5×106rad/s with a 1V amplitude. What is the current oscillation amplitude in amps
*Sunday, April 6, 2014 at 10:40am*

**physics**

Consider a coaxial cable with 2Amps in the center conductor coming out of the page, and 1Amp in the outer conductor going into the page. The center conductor has a radius of 1mm, the outer conductor's inner radius is 2mm, and the outer conductor's outter radius is 3mm...
*Sunday, April 6, 2014 at 8:59am*

**physics**

A brass ring of diameter 10.00 cm at 22.2°C is heated and slipped over an aluminum rod of diameter 10.01 cm at 22.2°C. Assume the average coefficients of linear expansion are constant. (b) What if the aluminum rod were 9.16 cm in diameter?
*Saturday, April 5, 2014 at 8:53pm*

**Physics**

A 215-kg load is hung on a wire of length of 3.50 m, cross-sectional area 2.000x10^-5 m2, and Young's modulus 8.00x 10^10 N/m2. What is its increase in length?
*Saturday, April 5, 2014 at 5:36pm*

**Physics**

One end of a uniform 3.20-m-long rod of weight Fg is supported by a cable at an angle of θ = 37° with the rod. The other end rests against the wall, where it is held by friction as shown in the figure below. The coefficient of static friction between the wall and the...
*Saturday, April 5, 2014 at 5:35pm*

**Physics 141**

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, there comes a ...
*Saturday, April 5, 2014 at 4:54pm*

**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...
*Saturday, April 5, 2014 at 4:30pm*

**Physics 141**

x=3.5cos(8pi.t) Amplitude=3.5m Frequency?
*Saturday, April 5, 2014 at 4:11pm*

**Physics 141**

x=3.5Cos(8pi.t) Amplitude=3.5m What is the frequency?
*Saturday, April 5, 2014 at 4:08pm*

**Physics**

Acceleration due to gravity is independent of mass, but the force is not. Determine the final velocity of the following objects and the force generated by the same objects as they are dropped from the given heights. 10 kg 2.5 meters 7 kg 5.5 meters 0.5 kg 12 meters 0.7 kg 5 ...
*Saturday, April 5, 2014 at 2:17pm*

**physics**

An industrial laser is used to burn a hole through a piece of metal. The average intensity of the light is S = 1.13 109 W/m2. What is the rms value of each of the following fields in the electromagnetic wave emitted by the laser? (a) electric field (b) magnetic field
*Saturday, April 5, 2014 at 11:41am*

**physics**

A 3.1-µF capacitor has a voltage of 31 V between its plates. What must be the current in a 5.6-mH inductor so that the energy stored in the inductor equals the energy stored in the capacitor?
*Saturday, April 5, 2014 at 11:36am*

**physics**

In a dentist's office, an X-ray of a tooth is taken using X-rays that have a frequency of 7.01 1018 Hz. What is the wavelength in vacuum of these X-rays?
*Saturday, April 5, 2014 at 11:36am*

**College Physics **

Two forces, F⃗ 1 and F⃗ 2, act at a point, as shown in the picture. (Figure 1) F⃗ 1 has a magnitude of 8.20N and is directed at an angle of α = 55.0∘ above the negative x axis in the second quadrant. F⃗ 2 has a magnitude of 6.40N and is ...
*Saturday, April 5, 2014 at 6:48am*

**physics**

A bomb of mass M at rest explodes into three pieces in the ratio 1 : 1 : 2. The smaller ones are thrown off in perpendicular directions with velocities 3 ms−1 and 4 ms−1. What is the velocity of the third piece after the explosion?
*Saturday, April 5, 2014 at 1:33am*

**Physics**

A pitcher throws a 0.192-kg baseball, and it approaches the bat at a speed of 43.2 m/s. The bat does 69.8 J of work on the ball in hitting it. Ignoring air resistance, determine the speed of the ball after the ball leaves the bat and is 32.6 m above the point of impact.
*Friday, April 4, 2014 at 8:49pm*

**Physics**

I'm having trouble setting up/solving this physics problem? Can someone please help me? Thank you. A 4700 kg lunar lander is in orbit 45 km above the surface of the moon. It needs to move out to a 340-km-high orbit in order to link up with the mother ship that will take ...
*Friday, April 4, 2014 at 8:02pm*

**Physics**

An infinitely long thin metal strip of width w=12cm carries a current of I=10A that is uniformly distributed across its cross section. What is the magnetic field at point P a distance a=3cm above the center of the strip? I have tried using the integration method but cannot get...
*Friday, April 4, 2014 at 7:27pm*

**physics**

Two manned satellites approaching one another at a relative speed of 0.500 m/s intend to dock. The first has a mass of 3.50 ✕ 103 kg, and the second a mass of 7.50 ✕ 103 kg. Assume that the positive direction is directed from the second satellite towards the ...
*Friday, April 4, 2014 at 6:52pm*

**physics. PLEASE HELP**

Where do I start? 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. The question says to neglect the pressure due to atmosphere when doing my ...
*Friday, April 4, 2014 at 6:23pm*

**Physics**

An asteroid is moving along a straight line. A force acts along the displacement of the asteroid and slows it down. The asteroid has a mass of 4.5× 104 kg, and the force causes its speed to change from 7000 to 5000m/s. (a) What is the work done by the force? (b) If the ...
*Friday, April 4, 2014 at 6:22pm*

**PHYSICS**

A grinding wheel 0.3m in diametre has amass of 5kg is rotating at an angular velocity of 2300rev/min.what is the kinetic energy?
*Friday, April 4, 2014 at 4:23pm*

**PHYSICS**

A grinding wheel 0.3m in diametre has amass of 5kg is rotating at an angular velocity of 2300rev/min.what is the kinetic energy?
*Friday, April 4, 2014 at 4:16pm*

**Physics**

a 5 kg crate falls from a height of 2.0 m into an industrial spring scale. When the crate comes to rest the compression of the spring is 24 cm. what is the spring constant?
*Friday, April 4, 2014 at 4:09pm*

**Algebra **

I can't figure this out.. A physics student stands at the top of hill that has an elevation of 37 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 = –...
*Friday, April 4, 2014 at 3:04pm*

**Physics**

If an object has a work of 300J and a displacement of 20m, how would I determine the net force?
*Friday, April 4, 2014 at 2:18pm*

**Algebra**

A physics student stands at the top of hill that has an elevation of 37 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 = –0.02x² + 0.8x + 37 where ...
*Friday, April 4, 2014 at 12:41pm*

**Physics, science**

An electric kettle contain 1.5kg of water at 100 degree and powered by a 2.0kw electric element. He the thermostat of the kettle falls to operate, approximately how long will the kettle boil dry? (take the specific latent heat of vaporization of water as 2000kJkg
*Friday, April 4, 2014 at 10:02am*

**Physics**

A turntable rotates counterclockwise at 63 rpm. A speck of dust on the turntable is at θ = 0.57 rad at t = 0 s. What is the angle of the speck at t = 9.5 s? Your answer should be between 0 and 2π rad.
*Thursday, April 3, 2014 at 11:50pm*

**Physics!!!**

How much work W must be done on a particle with a mass of m to accelerate it from rest to a speed of 0.899c ? Express your answer as a multiple of mc^2 to three significant figures.
*Thursday, April 3, 2014 at 11:40pm*

**Physics!!**

A subatomic particle has a 410ns lifetime in its own rest frame. If it moves through the lab at 0.970 c, how far does it travel before decaying, as measured in the lab?
*Thursday, April 3, 2014 at 11:39pm*

**Physics**

A wheel 31.7 cm in diameter accelerates uniformly from 238 rpm to 347 rpm in 5.9 seconds. How far will a point on the rim of the wheel have travelled in this time?
*Thursday, April 3, 2014 at 11:32pm*

**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 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 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**

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**

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 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!!**

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**

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**

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**

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 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**

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**

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*

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