A ball with a mass of 5 kg is rolling at 5 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 28, 2016

v_1^'=5/9" "m/s

v_2^'=50/9" "m/s

Explanation:

m_1=5" " kg
vec v_1=5 " "m/s

vec P_1=m_1*vec v_1
vec P_1=5*5=25 " "kg*m/s" momentum before collision for object " m_1

m_2=4" "kg
vec v_2=0

vec P_2=m_2*vec v_2=4*0=0" the object with " m_2= 4 kg" has no momentum"

Sigma vec P_b=25+0=25 " "kg*m/s" total momentum before collision"

"post collision velocity of object with "m_1="5 kg"

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

v_1^'=(2*25)/(5+4)-5

v_1^'=50/9-5

v_1^'=50-45/9

v_1^'=5/9" "m/s

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

v_2^'=(2*25)/(5+4)-0

v_2^'=50/9" "m/s