<p>A 0.400 kg croquet ball makes an elastic head-on collision with a second ball initially at rest. The second ball moves off with half the original speed of the first ball.</p>
<p>(a) What is the mass of the second ball?</p>
<p>(b) What fraction of the original kinetic energy (ΔKE/KE) gets transferred to the second ball?</p>
<p>I don't know how to do this one at all, can someone show me how to do this one?</p>
<p>Thanks.</p>
<p>sounds like an elastic collison, KE is conserved</p>
<p>Very useful equation for elastic head-on collisions:</p>
<p>v1 + v1(final) = v2 + v2(final)</p>
<p>Here, v2 = 0 and v2(final) = (1/2)v1 …</p>
<p>Solve for v1, and then try your momentum equation. Hope this helps!</p>
<p>The initial KE is the KE of the croquet ball. KE is conserved because the collision is elastic and momentum is conserved because there are no outside forces acting on the system. Solve the system of equations. Good luck!</p>