Question icon
Grade upto college level Mechanics

How much power, in horsepower, must be developed by the engine of a 1600-kg car moving at 26 m/s ( = 94 km/h) on a level road if the forces of resistance total 720 N?

Profile image of Shane Macguire
11 Years agoGrade upto college level
Answers icon

1 Answer

Profile image of Deepak Patra
11 Years ago
We have to find out the power developed by the engine of a 1600-kg car moving at 26 m/s (= 94 km/h) on a level road if the forces of resistance total 720 N.
To obtain power (P), substitute 720 N for F and 26 m/s for v in the equation P = Fv,
P = Fv
= (720 N) (26 m/s)
= 18720 N. m/s
= (18720 N. m/s) (1 W/1 N.m/s)
= 18720 W
= (18720 W) ((1/745.7 hp) / W)
= 25.10 hp …… (2)
Rounding off to two significant figures, the power which is developed by the engine will be 25 hp.