Sunday

December 21, 2014

December 21, 2014

**Recent Homework Questions About Physics**

Post a New Question | Current Questions

**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 help please!!!!!!!!!**

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 1:50pm*

**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 help. please**

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 1:21pm*

**Physics help. pls**

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 1:21pm*

**physics**

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 1:06pm*

**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**

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 12:48am*

**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*

**physics**

A particle of mass and initial velocity strikes a stationary particle of mass . The collision is elastic. It is observed that after the collision the particles have equal and opposite velocities: Find (a) the ratio ; (b) the velocity of the CM (before and after the collision...
*Friday, November 21, 2014 at 5:57am*

**physics**

A car of mass 200g moving at 15.0m/s is accelerated to 25.0m/s in a time of 10.0 seconds determine the accelerating force and calculate the work done on the body
*Friday, November 21, 2014 at 4:18am*

**physics**

A 5 ft chain is sitting on a table with 2 ft hanging off (3 ft sitting on table). The table is 4 ft high, and the chain slides frictionless off the table. The chain weighs 15 lb. What is the velocity of the chain when it first hits the ground.
*Friday, November 21, 2014 at 12:51am*

**physics**

a race car starts from rest on a circular track.the car increases its speed at constant rate at as it goes 2.75 times around the track.find the angle that the total acceleration of the car makes with the radius connecting the centre of the track and the car at the moment the ...
*Friday, November 21, 2014 at 12:05am*

**Physics**

Two workers are sliding 310kg crate across the floor. One worker pushes forward on the crate with a force of 440N while the other pulls in the same direction with a force of 230N using a rope connected to the crate. Both forces are horizontal, and the crate slides with a ...
*Friday, November 21, 2014 at 12:03am*

**Physics**

A chair of weight 85.0N lies atop a horizontal floor; the floor is not frictionless. You push on the chair with a force of F = 45.0N directed at an angle of 34.0∘ below the horizontal and the chair slides along the floor. Using Newton's laws, calculate n, the ...
*Thursday, November 20, 2014 at 11:35pm*

**physics**

A motorcross racer covers one lap of a 1200 meter track on his motorcycle at a speed of 27 meters per second. How long does it take to ride one lap: A. In seconds? B. In minutes?
*Thursday, November 20, 2014 at 11:34pm*

**Physics**

A swimmer can swim at 3.9m/s in still water. What will the swimmer's speed be (relative to the shore) if he crosses a river that is flowing at 5.1m/s?
*Thursday, November 20, 2014 at 10:59pm*

**physics**

note ... find acceleration by using distance and time (ignore ”incline” ... just treat it like linear motion of object starting from rest). A 1.8 kg mass starts from rest and slides down an inclined plane 8.8×10−1 m long in 0.54 s. What net force is ...
*Thursday, November 20, 2014 at 10:16pm*

**Physics **

A particle moving at a velocity of 8 m/s in the positive x direction is given an acceleration of 7.4 m/s2 in the positive y direction for 1.7 s. What is the final speed of the particle? Answer in units of m/s
*Thursday, November 20, 2014 at 10:07pm*

**Physics**

A plane designed for vertical takeoff has a mass of 6.4 ✕ 103 kg. Find the net work done by all forces on the plane as it accelerates upward at 8.4 m/s2 through a distance of 30.0 m after starting from rest.
*Thursday, November 20, 2014 at 8:48pm*

**Physics**

A skier of mass 67.0 kg is pulled up a slope by a motor-driven cable. How much work is required to pull the skier 59 m up a 32° slope (assumed to be frictionless) at a constant speed of 2.0 m/s?
*Thursday, November 20, 2014 at 8:47pm*

**physics**

A 67.0 kg ice skater moving to the right with a velocity of 2.02 m/s throws a 0.12 kg snowball to the right with a velocity of 21.5 m/s relative to the ground. (a) What is the velocity of the ice skater after throwing the snowball? Disregard the friction between the skates and...
*Thursday, November 20, 2014 at 8:46pm*

**physics 1**

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 16m/s and the official's speed is 24m/s...
*Thursday, November 20, 2014 at 8:32pm*

**physics**

Suppose that a sprinter can reach maximum speed by accelerating uniformly for 1.7 seconds. What maximum speed must this sprinter maintain in order to equal the world's record of 19.5 seconds for 200 meters?
*Thursday, November 20, 2014 at 8:22pm*

**physics**

if a bird travels 150 cm for 10 sec then 100 cm for 10 sec and then 200 cm for 5 sec. What was the birds average speed?
*Thursday, November 20, 2014 at 8:04pm*

**physics**

A 278 g particle is released from rest at point A inside an smooth hemispherical bowl of radius 36.5 cm, as shown below. (a) Calculate the gravitational potential energy at A relative to B. J (b) Calculate the particle's kinetic energy at B. J (c) Calculate the particle&#...
*Thursday, November 20, 2014 at 7:53pm*

**physics**

Tarzan swings on a 23.2 m long vine initially inclined at an angle of 22° from the vertical. (a) What is his speed at the bottom of the swing if he starts from rest? m/s (b) What is his speed at the bottom of the swing if he starts with an initial speed of 2.58 m/s? m/s
*Thursday, November 20, 2014 at 7:39pm*

**physics**

A student fires a rocket at 24 degrees above the horizontal. The 10kg rocket comes out of the gun barrel at 1000 m/s, and accelerates 15 m/s^2 uniformly until it burns out 2 seconds later. It then is acted apon by gravity until it hits the ground. I need to see a drawn out ...
*Thursday, November 20, 2014 at 7:33pm*

**Chemistry/Physics**

When 1mol of a gas burns at constant pressure, it produces 2430J of heat and does 5kJ of work. Calculate change in H, q, and in kJ?
*Thursday, November 20, 2014 at 7:30pm*

**Chemistry/Physics**

The kinetic energy of a rolling billiard ball is given by KE=1/2mv2. Suppose a 0.17-kg billiard ball is rolling down a pool table with an initial speed of 4.7m/s . As it travels, it loses some of its energy as heat. The ball slows down to 3.8m/s and then collides straight-on ...
*Thursday, November 20, 2014 at 7:27pm*

**ap 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 16m/s and the official's speed is 24m/s...
*Thursday, November 20, 2014 at 7:26pm*

**physics **

A 78 g basketball is launched at an angle of 45.4◦ and a distance of 10.1 m from the basketball goal. The ball is released at the same height (ten feet) as the basketball goal’s height. A basketball player tries to make a long jump-shot as described above. The ...
*Thursday, November 20, 2014 at 6:39pm*

**Physics-**

How can anything accelerate if every force has and equal and opposite counterpart?
*Thursday, November 20, 2014 at 6:20pm*

**physics**

A car (mass = 860 kg) is at rest on the top of a tall hill. the car rolls down the hill and at the bottom, reaches a top speed of 19 m/s. A) find the force of gravity on the car 560 x 9.8 = 5488 N B) find the work done by gravity on the car W = change in energy = kinetic ...
*Thursday, November 20, 2014 at 5:47pm*

**physics**

the motion of a body is described in simple harmonic motion as x=Cos(wt).when the body is 0.2m from the mid of its path , velocity is 3m/s and when it is 0.8m from the center of its path, its velocity is 1m/s ,determine: 1.the period 2.greatest acceleration
*Thursday, November 20, 2014 at 4:56pm*

**physics**

A box has mass 13 kg and is at rest on a flat floor. A minimum force of 47 N is needed to push the box so it moves across the floor. What is the coefficient of static friction between the box and floor?
*Thursday, November 20, 2014 at 4:24pm*

**physics**

A white billiard ball with mass mw = 0.1 kg is moving with a speed of v = 0.5 m/s making angle 60 degree and collides with a black billiard ball with the same mass mb = 0.1 kg that is initially at rest. The distance between the black ball and the pocket is 10cm\ friction exist...
*Thursday, November 20, 2014 at 2:59pm*

**physics**

A 4.53 kg particle has a velocity of vx = 3.98 m/s and vy = −3.16 m/s. Find the magnitude of its total momentum. Answer in units of kg · m/s
*Thursday, November 20, 2014 at 2:48pm*

**physics**

1) How many seconds does it take a car traveling 40 mph, decelerating at a rate of 7 miles per second, to come to a complete stop? 2) How many feet?
*Thursday, November 20, 2014 at 2:00pm*

**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)
*Thursday, November 20, 2014 at 11:08am*

**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?
*Thursday, November 20, 2014 at 10:14am*

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