Question

A passenger on a train traveling 90km/h on a straight, level track notes that it takes another train (180 m long and moving with constant velocity) 4.0s to pass by. What is the velocity of that passing train relative to the ground?

**please include explanation** thnx!!

Answer 1

The relative velocity is the distance divided by the time.

Now subtract the train moving 90km/hr, and you have the other train velocity.

Watch units.

Answer 2

so:
V = 180 m / 4 s = 45 m/s

convert to km/h

V = 162 km/h

This is the velocity relative to the first train, which is moving 90 km/h relative to the ground.

Then V = 162 + 90 km/h = 252 km/h

That's pretty fast...:-P