Impulse and linear momentum

A lorry of mass 20 000 kg is travelling at 20.0 m s^–1. A car of mass 900 kg is travelling at 30.0 m s^–1 towards the lorry. What is the magnitude of the total momentum?

• 209kNs

• 373kNs

• 427kNs

• 1045kNs

The diagram shows the masses and velocities of two trolleys about to collide.

After the impact they move off together. What is the total kinetic energy of the trolleys after the collision?

• 1.3J

• 19J

• 12J

• 18J

Two balls X and Y are moving towards each other with speeds of 5 m s^–1 and 15 ms^–1 respectively.

They make a perfectly elastic head-on collision and ball Y moves to the right with a speed of 7 m s^–1. What is the speed and direction of ball X after the collision?

• 3 m s^–1 to the left

• 13 m s^–1 to the left

• 3 m s^–1 to the right

• 13 m s^–1 to the right

Two balls, of masses m and 2m, travelling in a vacuum with initial velocities 2v and v respectively, collide with each other head-on, as shown.

After the collision, the ball of mass m rebounds to the left with velocity v. What is the loss of kinetic energy in the collision?

• 3/ 4 mv²

• 3/2 mv²

• 9/4 mv²

• 9/2 mv²

What is a statement of the principle of conservation of momentum?

• A force is equal to the rate of change of momentum of the body upon which it acts.

• n a perfectly elastic collision, the relative momentum of the bodies before impact is equal to their relative momentum after impact.

• The momentum of a body is the product of the mass of the body and its velocity.

• The total momentum of a system of interacting bodies remains constant, providing no resultant external force acts on the system.

The diagram shows two identical spheres X and Y.

Initially, X moves with speed v directly towards Y. Y is stationary. The spheres collide elastically. What happens?

• X moves with speed v to the right. Y moves with speed v to the right

• X moves with speed v to the left, Y remains stationary

• X moves with speed v to the left, Y moves with speed v to the right

• X stops, Y moves with speed v to the right

Two similar spheres, each of mass m and travelling with speed v, are moving towards each other.The spheres have a head-on elastic collision. Which statement is correct?

• The spheres stick together on impact.

• The total kinetic energy after impact is mv ² .

• The total kinetic energy before impact is zero.

• The total momentum before impact is 2mv.

An elastic collision occurs between two bodies X and Y. The mass of body X is m and the mass of body Y is 4m. Body X travels at speed v before the collision and speed 3v\5 in the opposite direction after the collision. Body Y is stationary before the collision.

What is the kinetic energy of body Y after the collision?

• 8/10 mv²

• 34/50 mv²

• 16/50 mv²

• 1/5 mv²

A player catches a ball of mass 150 gm moving at a rate of 20 m/s. If the process of catching is to be completed in 0.1 sec. What is the force exerted by the ball on the hands of the player?

• 3000 N

• 300 N

• 30 N

• 0.3 N

Which of the following is momentum closely related to?

• Power

• Impulse

• Kinetic Energy

• Force