Atrain car has a mass of 10,000 kg and is moving at +3.0 m/s. it strikes an identical train car that is at rest. the train cars combine.

what is the magnitude of the final velocity of the combined cars?

the final velocity of the combined cars after collision = +1.5 m/s

The plus sign to indicate that the velocity is directed in the same direction as the initial velocity of train car 1.

Explanation:

Given

Mass of train car 1 = 10,000 kg

Initial velocity of train car 1 = 3.0 m/s

Mass of train car 2 = 10,000 kg (they said the two train cars were similar)

Train car 2 was initially at rest, initial velocity of train car 2 = 0 m/s

Then it is given that the train cars combine (stick together) after collision, meaning the collision was inelastic.

Let the final velocity of the combined cars be v

This question can be solved using the laws of the conservation of Momentum.

Momentum before collision = Momentum after collision

Momentum before collision = (Momentum of train car 1 before collision) + (Momentum of train car 2 before collision)

= (10000)(3) +(10000)(0) = 30,000 kgm/s

Momentum after collision = (10,000 + 10,000)(v) = (20000v) kgm/s

Momentum before collision = Momentum after collision

30000 = 20000v

v = (30000/20000) = 1.5 m/s.

Hence, the final velocity of the combined cars after collision = +1.5 m/s (plus sign to indicate that the velocity is directed in the same direction as the initial velocity of train car 1)

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