Question

A 2-kg object is moving east at 9 m/s when it collides with a 8-kg object that is initially at rest. After the completely elastic collision, the larger object moves east at 1 m/s. Find the final velocity of the smaller object after the collision. (East is defined as positive. Indicate the direction with the sign of your answer.)
m/s

Answer 1

Solution:

A 2-kg object is moving east at 9 m/s when it collides with a 8-kg object that is initially at rest. After the completely elastic collision, the larger object moves east at 1 m/s. Find the final velocity of the smaller object after the collision

Mass of the object = m1 = 2kg

Velocity in the +x direction (East) = v1 = 9m/s

Mass of the 2nd object = m2 = 8 kg

Final velocity of m2 = v2f = 1m/s (+x direction)

Using Momentum conservation , m1v1+m2v2=m1v1f +m2v2f

=> 2 * 9 + 8*0 = 2 *v1f + 8* 1

=> 2v1f = 18 - 8 =10

=> Final velocity of smaller object after collision = v1f = 10/2 = +5 m/s East