A ball with a mass of #2 kg# moving at #7 m/s# hits a still ball with a mass of #5 kg#. If the first ball stops moving, how fast is the second ball moving?

1 Answer
marfre
Jun 16, 2018

#v_2 = 2.8 m/s#

Explanation:

Given: a ball #2 kg# and #v = 7 m/s# hits a stationary ball with #m = 5 kg#. The first ball stops moving, find how fast the second ball is moving.

Momentum #p = mv# must be conserved:

#m_1v_1 = m_1(0) + m_2v_2#

#2(7) = 0 + 5v_2#

#v_2 = 14/5 = 2.8 m/s#

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