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

Answer:

#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#