A ball with a mass of 2 kg is rolling at 1 m/s and elastically collides with a resting ball with a mass of 3 kg. What are the post-collision velocities of the balls?

1 Answer
Apr 25, 2016

u_1=-1/5 m/s
u_2=4/5 m/s

Explanation:

"given data:"
m_1=2kg
v_1=1m/s
"Momentum before collision for the first ball:"
vec P_1=m_1*v_1=2*1=2 kg*m/s

m_2=3 kg
v_2=0
"momentum before collision for the second ball:"
vec P_2=3*0=0

"Total momentum before collision:"
vec P_b=vec P_1+vec P_2
vecP_b=2+0=2 kg*m/s

"Velocities for post collision :"

u_1:"Post collision velocity of the first ball"

u_1=(2*vec P_b)/(m_1+m_2)-v_1

u_1=(2*2)/(2+3)-1

u_1=4/5-1

u_1=-1/5 m/s

u_2:"Post collision velocity of the second ball"

u_2=(2*vec P_b)/(m_1+m_2)-v_2

u_2=(2*2)/(2+3)-0

u_2=4/5 m/s