A car drives along a straight level frictionless road by an engine delivering constant power. Then velocity is directly proportional to :
Answer & explanation
Correct answer: option 3
\(P = Fv = M\frac{dv}{dt}v\)
Hence, v dv = \(\frac{P}{m} dt\)
On integration, we find : \(\int v dv = \int \frac{P}{m} dt\)
\(v^2 = \frac{P}{m}t\)
\(v \propto \sqrt{t}\)