Question

A car weighing $1000kg$ is going up an incline with a slope of ${\sin }^{-1}\left(2/25\right)$ at a steady speed of $18kmph$. If $g=10m{s}^{-2}$, the power of its engine is:

• A. $4kW$
• B. $50kW$
• C. $625kW$
• D. $25kW$

Answer 1

The correct option is A $4kW$

$\sin \theta =\frac{2}{25}$
Velocity $v=18km/h=18\times \left(\frac{5}{18}\right)m/s=5m/s$
Force applied is $F=mg\sin \theta =1000\times 10\times \frac{2}{25}=800N$
Power $P=Fv=800\times 5=4000W=4kW$