Question

A 12100 kg railroad car travels alone on a level frictionless track with a constant speed of 20.5 m/s. A 5850 kg load, initially at rest, is dropped onto the car. What will be the car's new speed?

Answer 1

An application of the law of conservation of linear momentum, in the horizontal direction, will tell you the answer.

Give it a try.

Adding a load by dropping from above will not change the horizontal momentum.

Answer 2

12100kg-5850kg=6250kg/100
1/2kv2

1/2(625)(20.5)^2=

131328.125m/s

Answer 3

umm, im sorry about that answer, but really? 131 thousand meters per second? might want to check your math there, that's 131 kilometers per second which is pretty fast...