Question

A 0.30-kg puck, initially at rest on a frictionless horizontal surface, is struck by a 0.20-kg puck that is initially moving along the x-axis with a velocity of 9.0 m/s. After the collision, the 0.20-kg puck has a speed of 5.4 m/s at an angle of θ = 53° to the positive x-axis.

a)Determine the velocity of the 0.30-kg puck after the collision.

magnitude-?

direction-? (from the positive X-axis)

(b) Find the fraction of kinetic energy lost in the collision.

Answer 1

Solution-

(a)Use the momentum conservation in x and y direction to find the velocity of 0.3 kg puck,

Momentum conservation in the x-direction,

......(1)

Momentum conservation in the y-direction,

......(2)

Substitute in equation 1

Now find V, use equation 2

The velocity of 0.3 kg Puck is 4.78 m/s towards 37 angles from the x-axis.

(b)

Find the initial kinetic energy and final kinetic energy to find loss,

......(3)

similarly final kinetic energy after the collision,

Use equation 3,

or 22 % of the initial energy is being lost.

Therefore, total friction energy loss in the collision is 1.76 J , or 22 % energy of the system is loss.