A ball with a mass of 5 kg is rolling at 14 m/s and elastically collides with a resting ball with a mass of 4 kg. What are the post-collision velocities of the balls?

1 Answer
May 26, 2016

v_1^'=14/9" "m/s

v_2^'=140/9 " "m/s

Explanation:

m_1=5" " kg
v_1=14" " m/s
"Momentum before collision for the object with mass of 5 kg"
P_1=m_1*v_1=5*15=70" "kg*m/s

m_2=4" "kg
v_2=0
"Momentum before collision for the object with mass of 4 kg"

P_2=m_2*v_2
P_2=4*0=0

"The total momentum of objects before collision"
Sigma P_b=P_1+P_2
Sigma P_b=70+0=70

"Post collision velocities :"

v_1^'=(2*Sigma p_b)/(m_1+m_2)-v_1

v_1^'=(2*70)/(5+4)-14

v_1^'=140/9-14

v_1^'=(140-126)/9

v_1^'=14/9 " "m/s

v_2^'=(2*Sigma p_b)/(m_1+m_2)-v_2

v_2^'=(2*70)/(5+4)-0

v_2^'=140/9" "m/s