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?

1 Answer
Mar 19, 2017

Answer:

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

Explanation:

#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#