A bicyclist is coasting straight down a hill at a constant speed. The mass of the rider and bicycle is 80.0 kg, and the hill is inclined at 14.0° with respect to the horizontal. Air resistance opposes the motion of the cyclist. Later, the bicyclist climbs the same hill at the same constant speed. How much force (directed parallel to the hill) must be applied to the bicycle in order for the bicyclist to climb the hill?
2006-10-16 16:39:31 · 2 answers · asked by Alan l 1 in Education & Reference ➔ Homework Help
Find the wind resistance force by finding the component of weight in the direction of travel. Coasting downhill at constant velocity means these forces are equal. To climb the hill at the same rate he has to apply enough force to overcome the component of weight in the directon of travel plus the wind resistance force found earlier.
2006-10-16 17:04:02 · answer #1 · answered by gp4rts 7 · 0⤊ 0⤋
You can resolve the weight vector into the downhill component, which will give the force of the air resistance. Going up the hill, that force must be applied twice: once against the air resistance, and once against gravity. So a single trig computation will do it.
2006-10-16 23:43:32 · answer #2 · answered by Anonymous · 0⤊ 0⤋