1. Calculate the momentum of an object of mass = 9 x 10-31 kg and a velocity of 4 x 104 m/s. Can you guess what object this could be? hint: sub atomic particle.
  1. A force of 7.2 N is applied for 0.01 s. What is the impulse? I = F x t
  1. What is the change in momentum produced on an object if 23 N force acts on it for 7 s? I = F x t =  mv = m (vf – vi)
  1. If a 5 N-s impulse is applied on a 0.5 kg ball which was initially at rest, find its final velocity?
  1. A blue billiard ball moving at 2 m/s undergoes a head-on elastic collision with a red ball of the same mass, initially at rest. Find the final velocities of (a) blue ball, (b) red ball.
  1. A skater moving at 3 m/s collides with another of the same mass moving at 4 m/s in the same direction. After collision they stick together. Find their final combined velocity.

mu1 + mu2 = (m + m) v

  1. A stone of mass 2 kg is thrown at an angle of 300 to the horizontal. Calculate the initial x and y components of its momentum if the velocity of throw is 3 m/s.

vx = v . cos vy = v . sin 

  1. If the initial momentum of a firecracker before explosion was zero and no external forces were acting on it, what would be the total sum of the momentums of its individual parts be after explosion?
  1. If in the above explosion, the parts were scattered in both x and y directions then what would be x component sum of momentums and the y component sum of momentums of its parts?
  1. If the initial x-momentum of a system is 4 kg m/s and its y-momentum is 3 kg m/s, what are the final x and y momentums? Consider no external forces are acting on it. What it the resultant momentum of the system?

Strategy for solving problems of collisions in 1-D

  1. Identify the objects in the system.
  2. If no external force acts on the system then, momentum is conserved.
  3. Identify the defining event to determine momentum before and after it. Example; collision or explosion
  4. Calculate the momentum of each object in the system before and after the event. Take the sum of momentum of all objects before and after the event separately.
  1. Equate the initial and final momentum of the system and solve for the unknown variable.

Strategy for solving problems of collisions in 2-D

  1. Resolve the momentum of all objects before and after the event into their x and y components. Calculate the x-momentum sum and y-momentum sum before and after the event separately.
  1. Equate the initial and final x-momentum sum to each other and the initial and final y-momentum sum to each other. This should be done individually for each component and solve for the unknown variable.
  1. When is a collision considered to be head – on? Hint: Centers of mass of two objects.
  1. In an automobile collision, which causes most damage to the vehicle? a) glancing collision, b) head – on collision, c) bumper – bumper collision
  1. Impulse is the product of average force and time of impact. When applied to an object it causes a change in that object’s momentum? What causes damage, the change in momentum or the average force applied?
  1. (a) Why does a coffee cup break when it falls on the hard floor but not when it drops on the carpet? (b) Is the impulse same in both cases; (c) Is the force same?
  1. What are the x and y momentums of a 1000 kg car traveling at 15 m/s, making an angle of 400 with the ground?
  1. A red billiard ball makes a glancing collision with a blue ball of the same mass, initially at rest. The collision is inelastic. The initial x-momentum of the red ball is 5 kg m/s and its y-momentum is zero. After the collision the red ball has a x-momentum of 3 kg m/s and y-momentum of 2 kg m/s. Find out the x and y momentum of the blue ball after collision.