Question

A train 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?

Answer 1

1.5 m/s that is the answer

Answer 2

Answer:

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)

Hope this Helps!!!