Question

A train has a constant speed of 40 m/s on a level road against resistive force of magnitude $3\times {10}^4$ N. Find the power of the engine.

• A. $1.2\times {10}^{6}W$
• B. $0.6\times {10}^{5}W$
• C. $0.6\times {10}^{6}W$
• D. $2.4\times {10}^{6}W$

Answer 1

The correct option is A $1.2\times {10}^{6}W$

At constant speed, there is no acceleration, so the forces acting on the train are in equilibrium.
Therefore, F=R
$\therefore F=3\times {10}^{4}NorP=Fv$
We have, power $=3\times {10}^4\times 40=1.2\times {10}^{6}W$