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# Velocity

### String Attached to a Block on a Horizontal Surface

Consider a string attached to a block on a horizontal surface. If you gradually pull very gently and horizontally on the string and increase the force very slowly until the block moves at a constant velocity. What happens to the frictional force just as the block begins to slide? Explain.

### Pulling a Cart

Please do not place your response in a .pdf or .cdx format, but Word documents are okay. Thanks! Here's the actual problem: Suppose that you have a cart with very little friction, and you pull this cart with a constant force. A) After the cart is moving, is the force that is applied to the cart by the string constant, i

The velocity of the slider block C is 4 ft/s up the inclined groove. Determine the angular velocity of links AB and BC and the velocity of point B at the instant shown. Links AB and BC are both 1ft in length. (See attachment for full question.)

### Angular Velocities of a Pulley

If the end of the cord is pulled downward with a speed Vc= 120mm/s, determine the angular velocities of pulleys A and B and the speed of block D. Assume that the cord does not slip on the pulleys. (See attachment for full question.)

### Projectile Motion with Coefficient of Restitution

The ball is ejected from the tube with a horizontal velocity of v1= 8ft/s as shown. If the coefficient of restitution between the ball and ground is e=0.8, determine (a) the velocity of the ball just after it rebounds from the ground and (b) the maximum height to which the ball rises after the first bounce (see attachment for di

### Pilots can be tested for the stresses of flying high speed jets in a whirling human centrifuge.

1) Automobile engine slows down from 4500 rpm to 1200 rpm in 2.5 s. Calculate (a) its angular acceleration, assumed constant, and (b) the total number of revolutions the engine makes in this time. 2) Pilots can be tested for the stresses of flying high speed jets in a whirling "human centrifuge," Which takes 1.0 min to turn t

### Average Landing Force Needed

A person about to jump from a 1.6m high platform wants to limit the average stopping force on landing to 12 times her weight. By how much will it be necessary to lower herself by flexing her knees? Give an algebraic rather than numerical answer. Compare that work with the original potential energy she had before she jumped.

### Physics Wave Problems

11. A particle in simply harmonic motion has a frequency of 40 Hz. What is the period of this oscillation? 17. (a) At what position is the speed of mass in a mass-spring system maximum? (1) x = 0, (2) x = -A, or (3) x = +A. Why? (b) If m = 0.250 kg, k = 100 N/m, and A = 0.10 m, what is the maximum speed? 33. The simple pe

### Calculating Recoil Velocity

Starting from rest, two skaters "push off" against each other on smooth level ice, where friction is negligible. The little one has a mass of 54-kg and the bigger one has a mass of 88-kg. Assuming the little one coasts away with a velocity of 2.5 m/s due north, determine the recoil velocity of the bigger skater.

### Average Force Exerted

A 140 gram baseball has a velocity of 38 m/s as it approaches a bat. The bat applies a force and the ball departs in the opposite direction at 58 m/s. The contact time between the bat and the ball is 4.0 ms. Determine the average force exerted on the ball by the bat.

### Hitting a tennis ball - the magnitude of the net impulse

The tennis ball has a horizontal speed of 15 m/s when struck by the racket. If it then travels away at an angle of 25 deg from the horizontal and reaches a maximum altitude of 10m, measured from the height of the racket, determine the magnitude of the net impulse of the racket on the ball. The ball has a mass of 180g. Neglect th

### Impulse of foot kicking soccer ball

A man kicks a 200g ball such that it leaves the ground at an angle of 30 deg. with the horizontal and strikes the ground at the same elevation a distance of 15m away. Determine the impulse of his foot on the ball. Neglect the impulse caused by the ball's weight while its being kicked. **answer should be 2.61 N*s**

### "Ball Kick"

A man kicks a 200g ball such that it leaves the ground at an angle of 30 degrees with the horizontal and strikes the ground at the same elevation a distance of 15m away. Determine the impulse of his foot on the ball. Neglect the impulse caused by the ball's weight while its being kicked.

### Block Up Ramp

A 5-lb block is given an initial velocity of 10 ft/s up a 45 degree smooth slope. Determine the time it will take to travel up the slope before it stops.

### Calculations for Shooting Over a Hill

Please do not place your response in a .pdf or .cdx format, but Word documents are okay. Thanks! Please see attached for actual problem.

### Velocity, Distance and Speed

The 2-lb brick slides down a smooth roof, such that when it is at A it has a velocity of 5ft/s. Determine the speed of the block just before it leaves the surface at B, the distance d from the wall where it strikes the ground, and the speed at which it hits the ground.

### Force, Velocity, Potential Energy (Energy Law)

A girl has a mass of 40kg and center of mass at G. If she is swinging to a maximum height defined by theta = 60 deg, determine the force developed along each of the four supporting posts such as AB at the instant theta = 0 deg. The swing is centrally located between the posts. *See attachment for diagram.

### Playing with a Water Hose

Here's the problem: Two children, Ferdinand and Isabella, are playing with a water hose on a sunny summer day. Isabella is holding the hose in her hand 1.0 meters above the ground and is trying to spray Ferdinand, who is standing 10.0 meters away. To increase the range of the water, Isabella places her thumb on the hose hole

### Collision: Calculating Force and Velocity

Just before it is struck by a racket, a tennis ball weighing 0.560 N has a velocity of (20.0i-4.0j) m/s. During the 3.00 ms that the racket and ball are in contact, the net force on the ball is constant and equal to (-380i+110j)N. What is the x-component of the impulse of the net force applied to the ball? What is the y-componen

### Conservation of momentum

Jonathan and Jane are sitting in a sleigh that is at rest on frictionless ice. Jonathan's weight is 800 N, Jane's weight is 600 N, and that of the sleigh is 1000 N. They see a poisonous spider on the floor of the sleigh and immediately jump off. Jonathan jumps to the left with a velocity (relative to the ice) of 5.00 m/s at 30 d

### Impulse Delivered to the Ball

A steel ball with mass 38.0 g is dropped from a height of 1.93 m onto a horizontal steel slab. The ball rebounds to a height of 1.56 m .Calculate the impulse delivered to the ball during impact. If the ball is in contact with the slab for a time of 2.40 ms, find the average force on the ball during impact.

### Analyzing Elastic Collision in One Dimension

Blocks of mass m and 2m are positioned on a semicircular frictionless track at a height of R/4 above the lowest point. The blocks are released simultaneously and collide elastically. How high does each block rise after the collision?

### Rocket Ejection and Linear Momentum

A rocket with initial mass of 8.0 x 10^3 kg is fired vertically. Its exhaust gases have a relative velocity of 2.5 x 10^3 m/s and are ejected at a rate of 40 kg/s. a) What is the initial accerleration of the rocket? b) What is the acceleration after 20s have elapsed?

### Streamlines and Fluid Flow

Please do not place your response in a .pdf or .cdx format, but Word documents are okay. Thanks! Please see attached for actual problem.

### Maximum Velocity of Center of Mass

A 1kg solid cylinder of radius 2cm is connected to a Hookes' law spring (k=100 N/m). The cylinder is displaced 20cm to the left and released. The cylinder rolls without slipping. Find the maximum velocity of the cylinder's center of mass.

### Newton's second law

The boy of mass 40kg is sliding down the spiral slide at a constant speed such that his position, measured from the top of the chute, has components r=1.5m, theta=(0.7t)rad, and z=(-0.5t)m, where t is in seconds. Determine components of force: F(subscript r), F(subscript theta), and F(subscript z) which the slide exerts on him a

### Speed of a plane with respect to another plane

Two planes A and B are flying side by side at a constant speed of 900km/h. Maintaining this speed, plane A begins to travel along the spiral path r = (1500*theta) km, where theta is in radians, whereas plane B continues to fly in a straight line. Determine the speed of plane A with respect to plane B when r=750km.

### Speed of Plane

Two planes A and B are flying side by side at a constant speed of 900km/h. Maintaining this speed, plane A begins to travel along the spiral path r = (1500*theta) km, where theta is in radians, whereas plane B continues to fly in a straight line. Determine the speed of plane A with respect to plane B when r=750km.

### Pendulum Loops Around a Nail

A pendulum of mass M is attached to a string of length L. The other end of the string is attached to pivot point P. The string and mass are held horizontal and released so that the mass swings down. When the mass is at its lowest point, the string hits a nail a distance h above the mass, so that the mass loops around the nail. W

### Angular momentum

A hockey stick of mass m_s and length L is at rest on the ice (which is assumed to be frictionless). A puck with mass m_p hits the stick a distance D from the middle of the stick. Before the collision, the puck was moving with speed v° in a direction perpendicular to the stick. The collision is completely inelastic, and the pu