Answer to Question #248237 in Physics for rshiii

Question

12. Two figure skaters, one weighing 625 N and the other 725 N, push off
against each other on frictionless ice. (a) If the heavier skater travels at
1.50 m/s, how fast will the lighter one travel? (b) How much kinetic
energy is à ¢ € œcreatedà ¢ €  during the skatersà ¢ € ™ maneuver, and where does this
energy come from?

Answer 1

(a) $|F_{12}|=|F_{21}|\to m_1v_1=m_2v_2\to$

$v_2=m_1v_1/m_2=(m_1g)v_1/(m_2g)=725\cdot1.5/625=1.74\ (m/s)$

(b) $E_k=m_1v_1^2/2+m_2v_2^2/2=(725/9.8)\cdot1.5^2/2+(625/9.8)\cdot1.74^2/2\approx180\ (J)$

Тhis energy come from the energy of chemical reactions in the muscles of figure skaters.