Question

Se lanza una pelota de hule elástica de masa mA con una velocidad VAi contra la puerta trasera de un camión muy pesado de masa mB que se encuentra en reposo ¿Cuáles son las velocidades de ambos objetos después de la colisión? Suponga un choque elástico.

Answer 1

Answer:

$v_{A}=v_{Ai}$

Explanation:

The total momentum of the system must conserve by the law of momentum conservation.

$p_b=p_a\\\\m_Av_{Ai}+m_Bv_{Bi}=m_Av_{A}+m_Bv_{B}$    ( 1 )

If you consider the shock between the ball and the truck as totally elastic, and also if the truck is much more massive than the ball, you can assume that the truck does not move when the ball hits it.

Then the truck is always at rest

Hence, you have in the expression ( 1 ):

$m_Av_{Ai}+0=m_Av_{A}+0\\\\v_{Ai}=v_{A}$