Exam 7: Momentum, Collisions, and the Center of Mass

Two masses M and 5M rest on a horizontal frictionless table with a compressed spring of negligible mass between them. When the spring is released, the energy of the spring is shared between the two masses in such a way that

A 40-kg girl, standing at rest on the ice, gives a 60-kg boy, who is also standing at rest on the ice, a shove. After the shove, the boy is moving backward at 2.0 m/s. Ignore friction. The girl's speed is

The condition necessary for the conservation of linear momentum in a given system is that

A uniform 12-inch ruler has a 5-g mass at the "1-inch" mark, and a 10-g mass at the "7-inch" mark. Where is the system's center of mass?

Two masses, m₁ and m₂, are moving with velocities and when they collide. After the collision, the final velocities are and . Which of the following expressions is true? The subscripts x and y represent the components along x and y respectively.)

A helium atom mass = 4m) moving with speed collides elastically with a deuterium hydrogen 2) atom mass = 2m) at rest. Calculate the percentage change in the kinetic energy of the helium atom after the collision.

A 20-g bullet with an initial velocity of 3.0  104 cm/s penetrates 6.0 cm into a stationary wall. The average force exerted on the bullet by the wall in bringing it to rest is approximately

For this question, assume that all velocities are horizontal and that there is no friction. Two skaters A and B are on an ice surface. A and B have the same mass M = 90.5 kg. Skater A is initially motionless, and then throws a ball with mass m = 200 g toward B with a speed v = 21.5 m/s relative to the ice. B catches the ball and throws it back to A with the same speed. After A catches the ball, his speed with respect to the ice is

While in horizontal flight at a speed of 20 m/s, a baseball of mass 0.11 kg is struck by a bat. After leaving the bat, the baseball has a speed of 29 m/s in a direction opposite to its original direction. The magnitude of the impulse given the ball is

For a system consisting of two particles that undergo an elastic collision,

A 20-g bullet is fired into a 2.0-kg block of wood placed on a horizontal surface. The bullet stops in the block. The impact moves the block + bullet) a distance of 5 m before it comes to rest. If the coefficient of kinetic friction between the block and surface is 0.25, calculate the speed of the block + bullet) system immediately after impact.

Two cars of equal mass travel in opposite directions at equal speeds. They collide in a perfectly inelastic collision. Just after the collision, their velocities are

A 200-g ball dropped from a height of 50 cm rebounds to a height of 35 cm after impact. The change in momentum of the ball is

You shoot an arrow with a mass of 0.54 kg at 45^o above the horizontal. The bow exerts a force of 125 N for 0.65 s. With no air resistance, the maximum height the arrow reaches is

A car having a total mass of 2250 kg and traveling at 72 km/h smashes into a tree. The car is stopped in 0.25 s. The driver of the car is not held in place by a seat belt or any other restraining device. Just after the impact but before the driver hits any part of the car, the acceleration of the driver is