A railroad freight car coasts along a level track. It collides and couples with a second car, initially at rest and with brakes released. What percentage of the freight car's initial energy is preserved in the two-coupled cars after collision?

A railroad freight car, mass 15972 #kg#, is allowed to coast along a level track at speed 2 #m/s#. It collides and couples with a 41386 #kg# loaded second car, initially at rest and with brakes released. What percentage of the initial kinetic energy of the 15972 #kg# car is preserved in the two-coupled cars after collision?

Answer 1

This is a Conservation of Momentum/Conservation of Energy question.

#m_1v_1=m_2v_2# Then, the initial Kinetic Energy is #U_{k1}=1/2m_1v_1^2# . Calculate #v_2# then plug that in to find #U_{k2}=1/2m_2v_2^2#.

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Answer 2

Adrian Ayala

The percentage of the freight car's initial energy preserved after collision is not possible to determine without additional information about the collision, such as whether it is elastic or inelastic.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.