Question

A 1250 kg car is stopped at a traffic light. A 3550 kg truck moving at 8.33 m/s hits the car from behind. If bumpers lock, how fast will the two vehicles move?

Answer 1

Answer:

the two vehicles will be moving at a speed of 6.16  m/s

Explanation:

This is a case of completely inelastic collision, therefore, the conservation of momentum can be written as:

$m_1\,v_1+m_2\,v_2=(m_1+m_2)\,v_f$

which given the information provided results into:

$m_1\,v_1+m_2\,v_2=(m_1+m_2)\,v_f\\(1250)\,(0)+(3550)\,(8.33)=(1250+3550)\,v_f\\29571.5=4800\,v_f\\v_f=6.16\,\,m/s$