A ball with a mass of #10kg# moving at #3 m/s# hits a still ball with a mass of #7 kg#. If the first ball stops moving, how fast is the second ball moving?

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Answer 1 · 2016-04-12T15:10:27

#v_2'=30/7 m/s#

#P_b:" total momentum before collision"#
#P_a:" total momentum after collision"#

#P_b=P_a" conservation of momentum"#

#m_1=10kg#
#v_1=3m/s#
#m_2=7kg#
#v_2=0#

#P_b=m_1*v_1+m_2+v_2#
#P_b=10*3+7*0#
#P_b=30+0#
#P_b=30 kg*m/s#

#P_a=m_1*v_1'+m_2*v_2'#
#P_a=10*0+7*v_2'#
#P_a=0+7v_2'#
#P_a=7v_2'#

#30=7v_2'#

#v_2'=30/7 m/s#