Exam 9: Linear Momentum and Collisions

A 2.0-kg object moving 3.0 m/s strikes a 1.0-kg object initially at rest.Immediately after the collision,the 2.0-kg object has a velocity of 1.5 m/s directed 30° from its initial direction of motion.What is the y component of the velocity of the 1.0-kg object just after the collision?

A 5.0-kg mass with an initial velocity of 4.0 m/s,east collides with a 4.0-kg mass with an initial velocity of 3.0 m/s,west.After the collision the 5.0-kg mass has a velocity of 1.2 m/s,south.What is the magnitude of the velocity of the 4.0-kg mass after the collision?

A U-238 nucleus (mass = 238 units)decays,transforming into an alpha particle (mass = 4.00 units)and a residual thorium nucleus (mass = 234 units).If the uranium nucleus was at rest,and the alpha particle has a speed of 1.50 × 10⁷ m/s,determine the recoil speed of the thorium nucleus.

At an instant when a particle of mass 80 g has a velocity of 25 m/s in the positive y direction,a 75-g particle has a velocity of 20 m/s in the positive x direction.What is the speed of the center of mass of this two-particle system at this instant?

A 3.0-kg object moving 8.0 m/s in the positive x direction has a one-dimensional elastic collision with an object (mass = M)initially at rest.After the collision the object of unknown mass has a velocity of 6.0 m/s in the positive x direction.What is M?

A pendulum consists of a 2.0-kg block hanging on a 1.5-m length string.A 10-g bullet moving with a horizontal velocity of 900 m/s strikes,passes through,and emerges from the block (initially at rest)with a horizontal velocity of 300 m/s.To what maximum height above its initial position will the block swing?

Two bodies of equal mass m collide and stick together.The quantities that always have equal magnitude for both masses during the collision are

A 1.6-kg ball is attached to the end of a 0.40-m string to form a pendulum.This pendulum is released from rest with the string horizontal.At the lowest point of its swing,when it is moving horizontally,the ball collides with a 0.80-kg block initially at rest on a horizontal frictionless surface.The speed of the block just after the collision is 3.0 m/s.What is the speed of the ball just after the collision?

A ball of mass m_B is released from rest and acquires velocity of magnitude v_B before hitting the ground.The ratio of the magnitude of the momentum the Earth acquires to the magnitude of the momentum the ball acquires is

A ball of mass m_B is released from rest and acquires velocity of magnitude v_B before hitting the ground.The ratio of the kinetic energy the Earth acquires to the kinetic energy the ball acquires is

Two blocks with masses 2.0 kg and 3.0 kg are placed on a horizontal frictionless surface.A light spring is placed in a horizontal position between the blocks.The blocks are pushed together,compressing the spring,and then released from rest.After contact with the spring ends,the 3.0-kg mass has a speed of 2.0 m/s.How much potential energy was stored in the spring when the blocks were released?

A 12-g bullet moving horizontally strikes and remains in a 3.0-kg block initially at rest on the edge of a table.The block,which is initially 80 cm above the floor,strikes the floor a horizontal distance of 120 cm from its initial position.What was the initial speed of the bullet?

A steel ball bearing of mass m₁ and speed of magnitude v₁ has a head-on elastic collision with a steel ball bearing of mass m₂ at rest.Rank the speed v₁ of m₁ relative to v₂,the magnitude of the speed of m₂,after the collision when i.m₁ > m₂;ii)m₁ = m₂;and iii)m₁ < m₂.

Exhibit 9-1 Two birds of prey hurtling after the same mouse collide in mid-air and grab each other with their talons.Each 250-g bird is flying at 30 m/s at a 60° angle to the ground. Use this exhibit to answer the following question(s). -Refer to Exhibit 9-1.What is the magnitude of their total momentum,in ,immediately after the collision?

A 4.0-kg particle is moving horizontally with a speed of 5.0 m/s when it strikes a vertical wall.The particle rebounds with a speed of 3.0 m/s.What is the magnitude of the impulse delivered to the particle?

A child bounces a 50-gram superball on the sidewalk.The velocity of the superball changes from 21 m/s downward to 19 m/s upward.If the contact time with the sidewalk is 1/800 s,what is the magnitude of the force exerted on the superball by the sidewalk?

A 1.2-kg object moving with a speed of 8.0 m/s collides perpendicularly with a wall and emerges with a speed of 6.0 m/s in the opposite direction.If the object is in contact with the wall for 2.0 ms,what is the magnitude of the average force on the object by the wall?

A rocket with an initial mass of 1000 kg adjusts its thrust by varying the rate at which mass is ejected.The ejection speed relative to the rocket is 40 km/s.If the acceleration of the rocket is to have a magnitude of 20 m/s² at an instant when its mass is 80% of the original mass,at what rate is mass being ejected at that instant? Ignore any external forces on the rocket.

Stan argues that momentum cannot be conserved when a collision is not a head-on collision.Rachel insists it is conserved because each body receives an impulse of equal magnitude.Rachel is correct because

An exam paper contains the following equation for rocket propulsion: ) The error in the equation is that,instead of (v + v_e),the velocity of the fuel relative to the ground should be