Sunday

May 3, 2015

May 3, 2015

**Math Physics**

What is the wavelength of an electromagnetic wave with frequency 50.0 MHz? Am I starting this problem like this? 3.00*10^8/50*10^6 =6*10^12
*Monday, November 24, 2014 at 1:58pm*

**Physics**

A 4.40kg block hangs from a spring with spring constant 2160N/m . The block is pulled down 4.60cm from the equilibrium position and given an initial velocity of 1.40m/s back toward equilibrium. A) What is the frequency of the motion? B) What is the amplitude? C) What is the ...
*Monday, November 24, 2014 at 1:01pm*

**physics**

is it possible to a have a percentage difference of zero in physics
*Monday, November 24, 2014 at 11:45am*

**Physics**

In our physics class we launched a rocket up into the air. We measured the time it took to go up to the point it reached the ground once again. How do I find the maximum height the rocket reached?
*Monday, November 24, 2014 at 11:41am*

**physics **

we did a lab and my observation chart is like this when my mass is 1.4 kgs (height is 0.12m,distance is 1.0m,time is 0.87s,velocity is 1.1 m/s ,Eg is 1.6 and the Ek is 0.85) when my mass is 2.14 kgs(height is 0.12m,distance is 1.0m,time is 0.88s,velocity is 1.1 m/s ,Eg is 2.8 ...
*Monday, November 24, 2014 at 11:24am*

**physics**

If an atom has an electron in the n = 5 state with ml = 3, what are the possible values of l?
*Monday, November 24, 2014 at 10:30am*

**physics**

it takes about 560 kilowatts to run a diesel locomotive at speed around 180km/h.Magnetically levitated trains(mag levs) on the other hand require less power because the magnetic levitation eliminates energy loss to friction.The worst maglev system requires 270 watts to ...
*Monday, November 24, 2014 at 10:17am*

**physics**

Please Help!! How much power is developed by a jumbo jet that cruises at 250 m/s. When the trust of its engine is 100,000 N? Thanks!!!
*Monday, November 24, 2014 at 6:01am*

**physics**

How much power is developed by a jumbo jet that cruises at 250 m/s. When the trust of its engine is 100,000N?
*Monday, November 24, 2014 at 6:00am*

**Physics**

A ball is thrown horizontally with a velocity of 40 m/s from the top of a building. Find its velocity and displacement after 3 s.
*Monday, November 24, 2014 at 4:57am*

**physics**

calculate the number of kilocalories needed to climb 232 stair steps (116 steps per minute for 2 min.) climbing stairs (116/min.) = energy consumption rate is 9.8 (kcal/min)
*Monday, November 24, 2014 at 3:28am*

**physics**

calculate minimum effort required to move load of 39 Newton in inclined plane whose length of slope is 39m ,height is 5m, distance from the base is 12m?
*Monday, November 24, 2014 at 1:05am*

**physics**

A(n) 1949.1 kg car is coasting along a level road at 22.9 m/s. A constant braking force is applied, such that the car is stopped in a distance of 74.6 m. What is the magnitude of the braking force? Answer in units of N
*Sunday, November 23, 2014 at 11:53pm*

**physics**

A(n) 1949.1 kg car is coasting along a level road at 22.9 m/s. A constant braking force is applied, such that the car is stopped in a distance of 74.6 m. What is the magnitude of the braking force? Answer in units of N
*Sunday, November 23, 2014 at 11:52pm*

**physics**

A 4.40kg block hangs from a spring with spring constant 2160N/m . The block is pulled down 4.60cm from the equilibrium position and given an initial velocity of 1.40m/s back toward equilibrium. What is the frequency of motion? What is the amplitude? What is the total ...
*Sunday, November 23, 2014 at 11:08pm*

**physics**

A 0.500kg ball is tied to the end of a 1.50m string and revolved so its andle thata is 35 degrees. a.) find the velocity of the ball (ans 2.43)
*Sunday, November 23, 2014 at 10:13pm*

**physics**

A 1.2kg lead ball is launched off a cliff top at 16m/s at an angle of 20 degrees above the horizontal. The height of the horizontal is 15m. Determine the net force acting on the lead ball that caused the ball to drop 4.0m from point P.
*Sunday, November 23, 2014 at 9:54pm*

**Physics**

An 8.00g bullet is fired at 220m/s into a 250g wooden block that is initially at rest. The bullet remains in the block and after the collision the two slide up a 30 degree incline. a) Solve for the velocity of the bullet block after the collision. b) Determine the distance ...
*Sunday, November 23, 2014 at 9:36pm*

**Physics**

A lathe, initially at rest, accelerates at .60 rad/s^2 for 10s, then runs at a constant angular velocity for 20s, and finally decelerates uniformly for 10s to come to a complete stop. What is its average angular velocity?
*Sunday, November 23, 2014 at 9:24pm*

**Physics**

The angular velocity of a wheel is given by w(t) = (2.00 rad/s^2)t + (1.00 rad/s^4)t^3. A. What is the angular displacement of the wheel from time t=0.00s to time t=T? B.What is the angular acceleration of the wheel as a function of time?
*Sunday, November 23, 2014 at 9:22pm*

**College Physics**

A thin rod (uniform density & thickness) has mass M and length L. It is attached to the floor at a fixed location by a friction-less hinge. The rod start at rest, balanced vertically on its hinge end. ______________________________________ 1) While balanced vertically, the ...
*Sunday, November 23, 2014 at 9:18pm*

**physics please help **

On the surface of a planet an object is thrown vertically upward with an initial speed of 60 m/s. use a conservation of energy approach to determine the object's speed when the object is at a quarter of it's maximum height. (assume the planet has no atmosphere) PLEASE ...
*Sunday, November 23, 2014 at 8:53pm*

**physics please help **

a 65 kg bag is dragged along a 12m ramp in order to get from the ground to the floor of the loading dock 2m above the ground. determine the efficiency of of the ramp. The frictional force acting on the bag is 50N due to the ramp. I don't understand how to the find the ...
*Sunday, November 23, 2014 at 8:43pm*

**Physics**

A thin rod (uniform density & thickness) has mass M and length L. It is attached to the floor at a fixed location by a friction-less hinge. The rod start at rest, balanced vertically on its hinge end. ______________________________________ 1) While balanced vertically, the ...
*Sunday, November 23, 2014 at 8:21pm*

**physics **

When a wave crosses a boundary between a thin and a thick rope, its frequency changes, but its wavelength and speed do not. True or false I think the answer is True
*Sunday, November 23, 2014 at 7:48pm*

**physics**

An object of mass 1.5 kg rests on a shelf where it has a gravitational potential energy of 7 joules. An object of mass 4.5 kg is placed on the same shelf. What is the gravitational potential energy of this second object?
*Sunday, November 23, 2014 at 7:38pm*

**PLEASE HELP PHYSICS**

True or False 1. The frequency of the wave can be changed by changing the frequency at which the waves are generated 2. Two crests are out of phase with each other. A crest and a trough are in phase with eachother 3. When a wave reaches the boundary of a new medium, part of ...
*Sunday, November 23, 2014 at 7:37pm*

**Physics**

A roll of toilet paper (a partially hollow cylinder with R_2 = 7.5cm, M = 300g, and I = 9.0 x 10^-4 kg m^2) is mounted on a mass-less axle along its central axis. Te roll is initially at rest. Then, at t=0, a child grabs the end of the roll and starts running, pulling the ...
*Sunday, November 23, 2014 at 7:29pm*

**physics**

a 65 kg bag is dragged along a 12m ramp in order to get from the ground to the floor of the loading dock 2m above the ground. determine the efficiency of of the ramp. The frictional force acting on the bag is 50N due to the ramp. I don't understand how to the find the ...
*Sunday, November 23, 2014 at 7:19pm*

**Physics **

True or false Wavelength is the distance between two adjacent points on a wave that are in phase My work I think it is false
*Sunday, November 23, 2014 at 6:54pm*

**Probability**

You have a blind date with a physics major. From your social networking experience, you know that 10% of physics majors are immature, 50% are narcissistic, and 90% are boring. Assume that immaturity, narcissism, and boringness are independent events. Calculate the probability ...
*Sunday, November 23, 2014 at 6:47pm*

**Physics**

A 0.118 kg baseball traveling with a horizontal speed of 3.14 m/s is hit by a bat and then moves with a speed of 33.7 m/s in the opposite direction. What is the magnitude of the change in the ball's momentum?
*Sunday, November 23, 2014 at 6:40pm*

**physics**

a 65 kg bag is dragged along a 12m ramp in order to get from the ground to the floor of the loading dock 2m above the ground. determine the efficiency of of the ramp. I don't understand how to the find the energy output and input.
*Sunday, November 23, 2014 at 6:30pm*

**Physics**

a projectile is fired at such an angel from the horizontal that the vertical componet of its velocity is 49m/s. the horizontal componet of its velocity is 61 m/s. what is the initial velocity of the projectile?
*Sunday, November 23, 2014 at 5:35pm*

**physics**

A sled on ice moves in the ways described in the questions below. Friction is so small that it can be ignored. A person wearing spiked shoes standing on the ice can apply a force to the sled and push it along the ice.Which force would keep the sled moving toward the right and ...
*Sunday, November 23, 2014 at 5:24pm*

**Physics **

True or false 1. When a wave reaches the boundary of a new medium,part of the wave can be reflected and part of the wave can be transmitted into the new medium. 2. When a wave crosses a boundary between a thin and a thick rope its frequency changes, but its wavelength and ...
*Sunday, November 23, 2014 at 5:10pm*

**Physics **

The frequency of the wave can be changed by changing the frequency at which the waves are generated. True or false My work I think the answer is false
*Sunday, November 23, 2014 at 4:41pm*

**physics**

Air at 1 atm is inside a cylinder 17.9 cm in radius and 17.9 cm in length that sits on a table. The top of the cylinder is sealed with a movable piston. A 24.1-kg block is dropped onto the piston. a) From what height above the piston must the block be dropped to compress the ...
*Sunday, November 23, 2014 at 4:27pm*

**Physics**

A projectile of mass 0.99 kg is shot from a cannon. The end of the cannon’s barrel is at height 6.6 m, as shown in the figure. The initial velocity of the projectile is 9.2 m/s. The projectile rises to a maximum height of ∆y above the end of the cannon’s barrel...
*Sunday, November 23, 2014 at 4:09pm*

**physics**

A proton moves with a velocity V (2i - 4 j + k) m / s in a region where the field is given by B = (i + 2 j -3k) T . What is the magnitude of the magnetic force experienced by the load?
*Sunday, November 23, 2014 at 3:53pm*

**physics**

Moving fast proton of 4x106 m / s through a 1.7 T magnetic field experiences a force 8x10-13N magnetic. What is the angle between the velocity vector associated with the proton and the magnetic field?
*Sunday, November 23, 2014 at 3:48pm*

**Physics**

A 4.40kg block hangs from a spring with spring constant 2160N/m . The block is pulled down 4.60cm from the equilibrium position and given an initial velocity of 1.40m/s back toward equilibrium. What is the frequency of motion? What is the amplitude? What is the total ...
*Sunday, November 23, 2014 at 3:45pm*

**Physics**

A piece of aluminum has a volume of 1.55 x 10-3 m3. The coefficient of volume expansion for aluminum is = 69 x 10-6(C°)-1. The temperature of this object is raised from 25.9 to 406 oC. How much work is done by the expanding aluminum if the air pressure is 1.01 x 105 Pa?
*Sunday, November 23, 2014 at 2:47pm*

**Physics**

A pond is 12 metres across. The crests of two successive waves are 60.0 cm apart and they each move across the pond in 15 seconds. a)What is the velocity of the waves? b)What is the frequency of the waves? c)What is the period of the waves?
*Sunday, November 23, 2014 at 2:12pm*

**Physics**

An aircraft landing on an aircrafts carrier is brought to a complete stop from an initial of 215km/h in 2.7 seconds. What is its acceleration in m/s2?
*Sunday, November 23, 2014 at 1:57pm*

**physics. I waited over two days for response**

An 800kg police boat slows down uniformly from 50km/h (E) to 20km/h(E) as it enters a harbour. If the boat slows down over a 30m distance, what is the force of friction of the boat? (Hint: you will need to convert the velocities into m/s) please show your work.
*Sunday, November 23, 2014 at 1:54pm*

**Physics**

A boy wants to throw a ball into his friend’s window 16.0 m above. Assuming it just reaches the window, he throws the ball at 55.0° to the ground. At what velocity should he throw the ball?
*Sunday, November 23, 2014 at 1:46pm*

**physics**

it takes about 560 kilowatts to run a diesel locomotive at speed around 180km/h.Magnetically levitated trains(mag levs) on the other hand require less power because the magnetic levitation eliminates energy loss to friction.The worst maglev system requires 270 watts to ...
*Sunday, November 23, 2014 at 12:19pm*

**Physics**

In a running event, a sprinter does 4.1 ✕ 105 J of work and her internal energy decreases by 8.1 ✕ 105 J.
*Sunday, November 23, 2014 at 12:07pm*

**Physics **

A certain car has an acceleration of 2.4m/s2.Assume that its acceleration remains constant. Starting from rest,how long does the car require to reach a velocity of 90km/h? How far does it travel while reaching that velocity?
*Sunday, November 23, 2014 at 11:39am*

**Physics**

An aircraft landing on an aircrafts carrier is brought to a complete stop from an initial of 215km/h in 2.7 seconds. What is its acceleration in m/s2?
*Sunday, November 23, 2014 at 11:31am*

**Physics**

A car accelerates from rest to 90km/h in 10 seconds.What is its acceleration in m/s2?
*Sunday, November 23, 2014 at 11:28am*

**physics**

a concrete slab of mass 400 kg accelerates down a concrete slope inclined at 35 degrees. the coefficient of kinetic friction between the slab and slope is 0.60. determine the acceleration of the block
*Sunday, November 23, 2014 at 10:48am*

**physics**

A ball thrown vertically upwards from ground level hits the ground after 4 seconds.Calculate the maximum height it reached during its journey.
*Sunday, November 23, 2014 at 10:34am*

**Physics**

What is the vector product of A=2i + 3j + 1k and B=1i - 3j - 2k?
*Sunday, November 23, 2014 at 12:31am*

**Physics**

A person pushes on a doorknob with a force of 5N. The direction of the force is at an angle of 20 degrees from the perpendicular to the surface of the door. The doorknob is located .800m from axis of the hinges of the door. The door begins to rotate with an angular ...
*Sunday, November 23, 2014 at 12:29am*

**Physics**

A two dimensional object placed in the xy plane has three forces acting on it: a force of 3N along the x axis acting at a point (3m, 4m); A force of 2N along the y axis acting at (-2, 5m); and a force of 5N in the negative x direction acting at (-2m, -3m). What is the net ...
*Sunday, November 23, 2014 at 12:23am*

**Physics**

A man is holding an 8.00kg vacuum cleaner at arm's length, a distance of .550m from his shoulder. What is the torque on the shoulder joint if the arm is held at 30degrees below the horizontal?
*Sunday, November 23, 2014 at 12:16am*

**physics**

In an effort to loosen the bolt on the wheel of a car, a man with a mass of 70kg steps on the end of a 50cm tire iron which is extending horizontally from the bolt. How much torque is he applying to the bolt?
*Sunday, November 23, 2014 at 12:12am*

**Physics**

A lathe, initially at rest, accelerates at .60 rad/s^2 for 10s, then runs at a constant angular velocity for 20s, and finally decelerates uniformly for 10s to come to a complete stop. What is its average angular velocity?
*Sunday, November 23, 2014 at 12:08am*

**Physics**

The angular velocity of a wheel is given by w(t) = (2.00 rad/s^2)t + (1.00 rad/s^4)t^3. A. What is the angular displacement of the wheel from time t=0.00s to time t=T? B.What is the angular acceleration of the wheel as a function of time?
*Sunday, November 23, 2014 at 12:04am*

**physics**

A spy in a speed boat is being chased down a river by government officials in a faster craft. Just as the officials’ boat pulls up next to the spy’s boat, both boats reach the edge of a 4.5m waterfall. The spy’s speed is 16 m/s and the officials’ speed is ...
*Saturday, November 22, 2014 at 11:46pm*

**physics**

Consider a very small hole in the bottom of a tank that is 17.0 cm in diameter and filled with water to a height of 90.0 cm. Find the speed at which the water exits the tank through the hole. A) 48.3 m/s B) 44.1 m/s C) 17.64 m/s D) 4.20 m/s
*Saturday, November 22, 2014 at 10:00pm*

**physics**

A skier of mass 70.4 kg, starting from rest, slides down a slope at an angle $\theta$ of 36.8° with the horizontal. The coefficient of kinetic friction is 0.14. What is the net work, i.e. net gain in kinetic energy, (in J) done on the skier in the first 8.4 s of descent?
*Saturday, November 22, 2014 at 9:54pm*

**physics**

A skier of mass 70.4 kg, starting from rest, slides down a slope at an angle $\theta$ of 36.8° with the horizontal. The coefficient of kinetic friction is 0.14. What is the net work, i.e. net gain in kinetic energy, (in J) done on the skier in the first 8.4 s of descent?
*Saturday, November 22, 2014 at 9:54pm*

**physics**

A skier of mass 70.4 kg, starting from rest, slides down a slope at an angle $\theta$ of 36.8° with the horizontal. The coefficient of kinetic friction is 0.14. What is the net work, i.e. net gain in kinetic energy, (in J) done on the skier in the first 8.4 s of descent?
*Saturday, November 22, 2014 at 9:53pm*

**Physics**

A roll of toilet paper (a partially hollow cylinder with R_2 = 7.5cm, M = 300g, and I = 9.0 x 10^-4 kg m^2) is mounted on a mass-less axle along its central axis. Te roll is initially at rest. Then, at t=0, a child grabs the end of the roll and starts running, pulling the ...
*Saturday, November 22, 2014 at 9:35pm*

**physics**

The acceleration of gravity is 9.8 m/s2 . What is the magnitude of the total force on a(n) 75 kg driver by the dragster he operates as it accelerates horizontally along a straight line from rest to 66 m/s in 4.5 s? Answer in units of kN
*Saturday, November 22, 2014 at 8:20pm*

**physics**

When a container of water is placed on a laboratory scale, the scale reads 120 g. Now a 20-g piece of copper (of density 8.9 g/cm3) is suspended from a thread and lowered into the water, not touching the bottom of the container. What will the scale now read? The density of ...
*Saturday, November 22, 2014 at 7:43pm*

**Physics**

Aqua dude can swim at a speed of 2.0m/s in still water. A river is 48 m wide and has a current of 1.5 m/s [E]. He starts at the Southbank and swims so that he is always headed directly across the river. A) what is Aqua dudes velocity relative to the shore? B) how long does it ...
*Saturday, November 22, 2014 at 7:34pm*

**physics**

A Venturi meter is a device for measuring the speed of a fluid within a pipe. The drawing shows a gas flowing at speed v2 through a horizontal section of pipe whose cross-sectional area is A2 = 0.0769 m2. The gas has a density of ρ = 1.30 kg/m3. The Venturi meter has a ...
*Saturday, November 22, 2014 at 4:21pm*

**physics**

A square with side lengths of 1.05 m has a charge of 8.00 mC at each corner. Calculate the magnitude and direction of the force on each charge
*Saturday, November 22, 2014 at 3:58pm*

**physics Pls help **

A piece of glass has a temperature of 87.0 °C. Liquid that has a temperature of 32.0 °C is poured over the glass, completely covering it, and the temperature at equilibrium is 57.0 °C. The mass of the glass and the liquid is the same. Ignoring the container that ...
*Saturday, November 22, 2014 at 3:49pm*

**Physics**

A 4.0-kg cylinder of solid iron is supported by a string while submerged in water. What is the tension in the string? The density of iron is 7860 kg/m3 and that of water is 1000 kg/m3. A) 34 N B) 2.5 N C) 24 N D) 40 N E) 20 N
*Saturday, November 22, 2014 at 3:46pm*

**Physics**

A water tank is filled to a depth of 10 m, and the bottom of the tank is 20 m above ground. A water-filled hose that is 2.0 cm in diameter extends from the bottom of the tank to the ground, but no water is flowing in this hose. The water pressure at ground level in the hose is...
*Saturday, November 22, 2014 at 1:19pm*

**Physics**

A 4 kg bundle starts up a 30o incline with 128 J of kinetic energy. How far will it slide up the incline if the coefficient of friction between bundle and incline is 0.30? Pls help me solve this, I dont know what formula to use...
*Saturday, November 22, 2014 at 6:54am*

**physics**

an ice skater applies a horizontal force to a 20 kg block on frictionless, level ice causing the block to accelerate uniformly at 1.4 m/s^2 to the right. after the skater stops pushing the block it slides onto a region of ice that is covered with a thin layer of sand. the ...
*Friday, November 21, 2014 at 10:31pm*

**Physics**

1. A student lifts his 2.0-kg pet rock 2.8m straight up. He then lets it drop to the ground. Use the Law of Conservation of Energy to calculate how fast the rock will be moving ..... a. half way down b. just before it hits the ground 2. A 65-kg girl is running with a speed of ...
*Friday, November 21, 2014 at 10:23pm*

**Physics**

1. Determine the specific heat of a certain metal if a 450-g sample of it loses 34,500 joules of heat as its temperature drops by 97degC. 2. The temperature of a 55-g sample of a certain metal drops by 113degC as it losses 3,500 J of heat. What is the specific heat of the ...
*Friday, November 21, 2014 at 10:22pm*

**physics**

The position versus time for a certain object moving along the x-axis is shown. The object’s initial position is −2 m. Find the instantaneous velocity at 6 s. Answer in units of m/s
*Friday, November 21, 2014 at 9:47pm*

**Physics**

Two disks are rotating about the same axis. Disk A has a moment of inertia of 3.1 kg · m2 and an angular velocity of +8.0 rad/s. Disk B is rotating with an angular velocity of -10.2 rad/s. The two disks are then linked together without the aid of any external torques, ...
*Friday, November 21, 2014 at 8:51pm*

**Physics**

Starting from rest, a basketball rolls from the top of a hill to the bottom, reaching a translational speed of 3.83 m/s. Ignore frictional losses. (a) What is the height of the hill? I've tried to use the mgh=1/2mv^2. I think it's because it's translational speed. ...
*Friday, November 21, 2014 at 8:23pm*

**Physics**

A wheel starts from rest and rotates about its axis with constant angular acceleration. After 8.7s have elapsed, it has rotated through an angle of 20 radians. What is the angular acceleration of the wheel? What is the angular velocity when the time t = 8.7 s? I got the answer...
*Friday, November 21, 2014 at 6:11pm*

**Physics **

A marble rolls down an incline of 30 degrees. If the marble is initally at rest at the top of the incline of length 2.0 meters what will the speed of the marble be at the bottom of the incline (a) if the incline is rough enough to prevent any slipping [ it rolls],then (b) if ...
*Friday, November 21, 2014 at 6:08pm*

**Physics**

An airplane flies at a constant speed in a straight line. A bale of hay is dropped from the bottom of the plane to some cattle in a snowstorm. When the bale hits the ground, where is the plane? (Ignore air resistance) Explain your answer!
*Friday, November 21, 2014 at 6:01pm*

**physics**

A launching mechanism consists of an arm (uniform rod with mass 250. g and length 75.0 cm) with a holder (negligible mass) at one end mounted to a hub of radius 3.00 cm and negligible mass at the other end. A string is wrapped around the hub and passes to a spring of constant ...
*Friday, November 21, 2014 at 4:52pm*

**Physics**

A volleyball court is 18 m long from baseline to baseline and the net is 2.24 m high. A volleyball player serves the ball from the baseline by hitting it at a height of 2 m above the floor at an angle of 10 degrees above the horizontal. A.) If the ball is in the air for 1.05 s...
*Friday, November 21, 2014 at 4:16pm*

**Physics**

A wheel starts from rest and rotates about its axis with constant angular acceleration. After 8.7s have elapsed, it has rotated through an angle of 20 radians. What is the angular acceleration of the wheel? What is the angular velocity when the time t = 8.7 s? I got the answer...
*Friday, November 21, 2014 at 3:52pm*

**Physics**

An iron disk has a radius of 0.625 m and a mass of 217 kg. The disk is mounted on its axis so that it is free to spin. How much force is required if the force is applied at a distance 19.5 cm from the axis of rotation?
*Friday, November 21, 2014 at 3:27pm*

**physics **

A bowling ball of mass 9 kg hits a wall going 11 m/s and rebounds at a speed of 8 m/s. What was the impulse applied to the bowling ball?
*Friday, November 21, 2014 at 3:27pm*

**physics**

A clock has a second hand whose tip rubs against the inside of the glass cover. If the frictional force between the glass cover and the tip of the second hand is 0.0010 N and the length of the hand is 6.5 cm, what is the minimum torque that must be applied to the second hand ...
*Friday, November 21, 2014 at 3:21pm*

**physics**

A 30-caliber rifle with a mass of 2.80 kg fires a 9.84- g bullet with a speed of 726 m/s with respect to the ground. What kinetic energy is released by the explosion of the gunpowder that fires the bullet?
*Friday, November 21, 2014 at 2:25pm*

**Physics**

A 24.5-kg child is standing on the outer edge of a merry-go-round which has moment of inertia 989 kg • m2 and radius 2.40 m. The entire system is initially rotating at 0.180 rev/s. Find the angular velocity if the child moves to a final position 1.10 m from the center of ...
*Friday, November 21, 2014 at 1:45pm*

**Physics**

A wheel starts from rest and rotates about its axis with constant angular acceleration. After 8.7 s have elapsed, it has rotated through an angle of 20 radians. I found that the angular velocity at 8.7 s is 4.60 rad/s. What is the angular acceleration of the wheel? What is the...
*Friday, November 21, 2014 at 1:21pm*

**Physics**

A clock has a second hand whose tip rubs against the inside of the glass cover. If the frictional force between the glass cover and the tip of the second hand is 0.0020 N and the length of the hand is 9.5 cm, what is the minimum torque that must be applied to the second hand ...
*Friday, November 21, 2014 at 1:19pm*

**Physics**

A 30-caliber rifle with a mass of 3.54 kg fires a 7.33- g bullet with a speed of 596 m/s with respect to the ground. What kinetic energy is released by the explosion of the gunpowder that fires the bullet? (Note there is a tolerance 0.1 percent for the answer)
*Friday, November 21, 2014 at 1:19pm*

**physics**

A dog sled team is pulling a sled across a flat patch of snow. The total force exerted by the four dogs is 475 N (applied horizontally). The sled (with driver on it) weighs 350 kg. and the coefficient of kinetic friction between the sled and the ground is (a) What is the ...
*Friday, November 21, 2014 at 11:44am*

**Physics**

A distant planet has a mass of 0.6400 ME and a radius of 0.9000 RE. What is the ratio of the escape speed from this planet to the escape speed from the earth?
*Friday, November 21, 2014 at 11:20am*

**Physics**

2 vectors have same magnitude.The magnitude of the resultant vector of these 2 vectors are same as either of both vectors.What is the angle between 2 vectors?
*Friday, November 21, 2014 at 7:18am*

**physics**

If the athlete lies down on the ground on his back,his weight is spread over an area of 0.75 meter square. How much pressure does he exert on the ground in this position?
*Friday, November 21, 2014 at 6:06am*