Physics

Physics

Problem

A car travels east with speed 20 m/s and then travels west with the same speed. If its initial momentum is p\mathbf{p} and its initial kinetic energy is KK, which option correctly states the momentum p′\mathbf{p}' and kinetic energy K′K' after the direction reversal? a) p′=p,  K′=K\mathbf{p}'=\mathbf{p},\;K'=K b) p′=−p,  K′=−K\mathbf{p}'=-\mathbf{p},\;K'=-K c) p′=−p,  K′=K\mathbf{p}'=-\mathbf{p},\;K'=K d) p′=−2p,  K′=2K\mathbf{p}'=-2\mathbf{p},\;K'=2K

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