Question

A motor of 100 H.P. is moving with a constant velocity of 72 km/hour. The forward force exerted by the engine on the car is

• A. $3.73\times {10}^{3}N$
• B. $3.73\times {10}^{2}N$
• C. $3.73\times {10}^{1}N$
• D. None of the above

Answer 1

The correct option is A $3.73\times {10}^{3}N$

Given that

$P=100HP=74600W$

$v=72Kmhou{r}^{-1}=\frac{72000}{3600}m{s}^{-1}=20m{s}^{-1}$

We know

$P=Fv$

Hence, the forward force exerted by the engine on the car is

$F=\frac{P}{v}$

$F=\frac{74600}{20}=3.73\times {10}^{3}N$