Question

Ben (55kg) is standing on very slippery ice when Junior (25kg) bumps into him. Junior was moving at a speed of 8 m/s before the collision and ben and junior embrace after the collision. Find the speed of ben and junior as they move across the ice after the collision. Give the answer in m/s. describe the work you did to get the answer.

Answer 1

Answer:

2.5 m/s

Explanation:

The total momentum before and after the collision must be conserved.

Before the collision, the total momentum is just given by Junior's momentum, since Ben is at rest. So,

$p_i = m_J u_J$

where

$m_J = 25 kg$ is Junior's mass

$u_J = 8 m/s$ is the Junior's initial velocity

So we find

$p_i = (25 kg)(8 m/s)=200 kg m/s$

The final momentum will be equal to the initial momentum:

$p_f = p_i$

and it can be written as

$p_f = (m_B + m_J) v$

where

$m_B = 55 kg$ is Ben's mass

v is their final velocity

Solving for v,

$v=\frac{p_f}{m_B + m_J}=\frac{200 kg m/s}{55 kg + 25 kg}=2.5 m/s$