posted by Allison .
If 7.00hp are required to drive a 1500-kg automobile at 66.0 km/h on a level road. What power is necessary to drive the car at 66.0 km/h down a 1.00 % grade? It requires 42.9 hp to drive the car at 66.0 km/h up a 10.0 % grade (a hill rising 10.0 m vertically in 100.0 m horizontally)? The total retarding force due to friction, air resistance, and so on is 285 N.
Is the following a statement of fact or a question?
<< It requires 42.9 hp to drive the car at 66.0 km/h up a 10.0 % grade (a hill rising 10.0 m vertically in 100.0 m horizontally)? >>
It is a fact.
Then why the question mark at the end?
Assume 35.9 extra hp is needed to provide the potential energy increase at that speed and 10% positive slope. At 1/10 the slope (1%) downwards, 3.6 hp is recovered from gravity, so the engine needs to provide only 3.4 hp.