The bullet with mass $$m_{ball}=0.2 kg$$ travels with speed $$v=2 \frac{m}{s}$$ and hits Plasticine sphere with mass $$m_{sphere}=2.5 kg$$ and get stuck. I need to find the amount of heat ejected. How to approach this task? Probably it's about kinetic energy transforming to heat; and the law of conservation of momentum.


closed as off-topic by jinawee, Brandon Enright, John Rennie, Kyle Kanos, user10851 Mar 13 '14 at 6:08

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "Homework-like questions should ask about a specific physics concept and show some effort to work through the problem. We want our questions to be useful to the broader community, and to future users. See our meta site for more guidance on how to edit your question to make it better" – jinawee, Brandon Enright, John Rennie, Kyle Kanos, Community
If this question can be reworded to fit the rules in the help center, please edit the question.


The velocity of the system after collision is $$ V=\frac{m_b}{m_b+m_s}v_b $$

The lost of kinetic energy can be assumed as the ejected heat in question, \begin{align} \Delta KE &= m_b v_b^2 /2 - (m_b+m_s)V^2 /2\\ &= m_b v_b^2 /2 - \frac{m_b^2}{m_b+m_s}v_b^2 /2\\ &= m_b v_b^2/2 \left(1-\frac{m_b}{m_b+m_s} \right)\\ &= \frac{m_b m_s}{m_b+m_s}v_b^2/2 \\ \end{align}


Not the answer you're looking for? Browse other questions tagged or ask your own question.