WORK, ENERGY & THEOREM

Q1. A cyclist and his bicycle has a mass of 80 kg. After 100m he reaches the top of a hill, with slope 1 in 20 measured along the slope, at a speed of 2 m/s. He then free wheels the 100m to the bottom of the hill where his speed has increased to 9m/s.
How much energy has he lost on the hill?
Solution

Figure 3.3: Dimensions of the hill in worked example 3.5
If the hill is 100m long then the height is:
So potential energy lost is
Increase in kinetic energy is
By the principle of conservation of energy



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