In: Physics
I suppose the assumption is: "The efficiencies of low-speed chairlifts and high-speed chairlifts are the same if they travel same distance".
a) The ball bearing friction decreases with increase in speed and the drag force on the chairs due to air resistance increases with increase in speed. The effect of drag force is much larger than the ball bearing friction. In fact, the drag force is directly proportional to the square of the speed and to the cross sectional area of the chairs. The formula for the drag force due to air resistance is given by:
where, FD is the drag force, is the density of the air, v is the speed of the obect relative to air, CD is the drag coefficient and A is the cross-sectional area of the object.
Therefore, high speed chairlift experiances more friction than low speed chairlift.
b) As the high speed chairlift experiances more friction than low speed chairlift, more energy needs to be consumed to operate high speed chairlift. Therefore, high speed chairlift is less energy efficient than low speed chairlift. Therefore the assumption is false.
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