A ball with a mass of $6 kg$ is rolling at $25 m/s$ and elastically collides with a resting ball with a mass of $2 kg$ . What are the post-collision velocities of the balls?

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Answer 1 · 2017-03-19T19:09:15

$"The post collision velocities : "v_1^'=12,5" "m/s" , "v_2^'=37.5" "m/s$

$m_1=6" "kg$
$m_2=2" "kg$
$v_1=25" "m/s$
$v_2=0$

$v_1^'=?$
$v_2^'=?$

$"Find total momentum before collision."$

$"let "Sigma P_b " be total momentum before collision"$

$Sigma P_b=m_1v_1+m_2*v_2$

$Sigma P_b=6*25+2*0$

$Sigma P_b=150" "kg.m/s$

$"Now ,calculate post collision velocities."$

$v_1^'=(2*Sigma P_b)/(m_1+m_2)-v_1" , "v_1^'=(2*150)/(6+2)-25=12,5" "m/s$

$v_2^'=(2*Sigma P_b)/(m_1+m_2)-v_2" , "v_1^'=(2*150)/(6+2)-0=37,5" "m/s$

A ball with a mass of 6 kg 6 kg is rolling at 25 m/s25 m/s and elastically collides with a resting ball with a mass of 2 kg 2 kg. What are the post-collision velocities of the balls?