Physics

Problem

Two gliders of masses

m_1

and

m_2

move along a frictionless air track. Glider 2 is initially at rest, and glider 1 has initial speed

v_{1i}

. The gliders collide elastically. Which expression gives the speed of glider 1 immediately after the collision? a)

v_{1f}=\dfrac{2m_2}{m_1+m_2}\,v_{1i}

v_{1f}=\dfrac{m_1-m_2}{m_1+m_2}\,v_{1i}

v_{1f}=\dfrac{m_2-m_1}{m_1+m_2}\,v_{1i}

v_{1f}=\dfrac{2m_1}{m_1+m_2}\,v_{1i}