A 7150-kg railroad car travels alone on a level frictionless track with a constant speed of 24.5 m/s. A 3100-kg load, initially at rest, is dropped onto the car What will be the car's new speed?

Car's new speed is 17.09 m/s

Explanation:

Here momentum is conserved.

Initial momentum = Final momentum

Initial mass = 7150 kg

Initial velocity = 24.5 m/s

Final mass = 7150 + 3100 = 10250 kg

Final velocity = v = ?

We have

Initial momentum = Final momentum

7150 x 24.5 = 10250 x v

v = 17.09 m/s

Car's new speed is 17.09 m/s