An electric train develops a power of 1.0 MW when travelling at a constant speed of 50 ms−1. The net?

Question

resistive force acting on the train is

A. 50 MN.
B. 200 kN.
C. 20 kN.
D. 200 N.

I got B, i pretty certain, if its not please explain your answer, i doubt i made arithmetic mistak,e and explain your unit usage.

Answer 1

Using SI units we have P = 1.0×10^6 W and v = 50 ms^-1.
P = Fv, so F = P/v = (1.0×10^6) / 50 = 2.0×10^4 N = 20 kN. So C is correct. If you got B, you either made a mistake or misunderstood the SI unit prefixes.