A vehicle that weights 400 N on the surface of the Earth is traveling in outer space at a speed of 400 m/s . It can be stopped by applying a constant force of 20 N for
A) 2 seconds.
B) 400 seconds.
C) 4 seconds.
D) 800 seconds.
E) 80 seconds.

Question

Quizplus · Accepted Answer

The momentum of the vehicle is mass times velocity. The mass is 400 N / 9.8 m/s² = 40.82 kg. The momentum is 40.82 kg * 400 m/s = 16328 kg*m/s. To stop it, apply a force of 20 N for time t: 20 N * t = 16328 kg*m/s, so t = 16328 / 20 = 816.4 seconds, which rounds to 800 seconds.

A Vehicle That Weights 400 N on the Surface of the Earth