6. A `5000`-`kg` boxcar traveling at `18.0\ m//s` strikes a second `4000`-`kg` boxcar at rest. The two cars stick together after the collision. What is the speed of the two cars after collision?
6. A 5000-kg boxcar traveling at 18.0\ m//s strikes a second 4000-kg boxcar at rest. The two cars stick together after the collision. What is the speed of the two cars after collision?
Hint
`p_i = p_f`
Answer
`v_f = 10.0\ m//s`
Show Steps
Given: `m_1 = 5000\ kg` `v_(1_i)=18.0\ m//s` `m_2= 4000\ kg` Equations: `p_i = p_f` Solution: `p_i = p_f` `=>` `m_1 v_(1_i) + m_2 v_(2_i) = m_1 v_(1_f) + m_2 v_(2_f)` From the given values `=>` `m_1 v_(1_i) + 0 = m_1 v_f + m_2 v_f` `=>` `m_1 v_(1_i) = (m_1 + m_2) v_f` `v_f =m_1/(m_1 + m_2) v_(1_i)` `v_f =(5000\ kg) /((5000\ kg)+(4000\ kg)) (18.0\ m//s)` `v_f = 10.0\ m//s`