April sits at rest on a skateboard. She has a mass of 65 kg. Her friend throws her a suitcase (m= 15 kg) at a speed of 3 m/s. If she catches it, how fast will
she, the skateboard, and the suitcase move?

Explanation:

Given

Represent mass of April with M and mass of the suitcase with m; such that

Represent initial velocity of April with U and initial velocity of the suitcase with u; such that

(because she's resting on the skateboard, initially)

After she catches the suitcase, she, the skateboard and the suitcase moves at the same velocity.

Represent this velocity with v

The above given information can be representing using law of conservation of momentum.

Substitute the values of M,U, m and u.

This gives

Divide both sides by 80

Hence, they moved at a velocity of 0.5625m/s

true is the correct answer

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