A ball with a mass of #9 kg# moving at #14 m/s# hits a still ball with a mass of #18 kg#. If the first ball stops moving, how fast is the second ball moving?

2 Answers
Md H S Shohrawardy
Dec 23, 2015

If the second ball is in rest before collision then after collision velocity of the second ball is 7m/s.

Shashwat S. · Grace
Dec 23, 2015

#7# #m#/#s#

Explanation:

#M_1#= mass of first ball, #V_1#= velocity of first ball
#M_2#= mass of second ball, #V_2#= velocity of second ball

by conservation of linear momentum

#M_1V_1 +M_2V_2=M_1V_1+M_2V_2#

9 x 14 + 18 x 0 = 9 x 0 + 18 x #V_2#

therefore #V_2# = #(9 " x " 14)/18# = #7# #m#/#s#

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