A ball with a mass of #10 kg# moving at #3 m/s# hits a still ball with a mass of #15 kg#. If the first ball stops moving, how fast is the second ball moving? How much kinetic energy was lost as heat in the collision?

1 Answer
Nam D.
Mar 17, 2018

#2 \ "m/s"# after the collision.

Explanation:

I'm not sure how to answer the second part of the question, but I can answer the first part.

So, we are going to use the law of conservation of momentum equation, which is

#m_1u_1+m_2u_2=m_1v_1+m_2v_2#

where #m_1,m_2# are the masses of the two objects, #u_1,u_2# are the initial velocities of the two objects, and #v_1,v_2# are the final velocities of the two objects.

So, plugging in the values, we get

#10 \ "kg"*3 \ "m/s"+15 \ "kg"*0 \ "m/s"=10 \ "kg"*0 \ "m/s"+15 \ "kg"*v_2#

#=>30 \ "kg m/s"=15 \ "kg"*v_2#

#v_2=(30color(red)cancelcolor(black)"kg""m/s")/(15color(red)cancelcolor(black)"kg")#

#=2 \ "m/s"#

So, the second ball will move at #2 \ "m/s"# after the collision.

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