By how much does his gravitational potential energy change during this climb?

63.5 kJ

Explanation:

Here is the complete question

A 72 kg bike racer climbs a 1200-m-long section of a road that has a slope of 4.3 degrees. By how much does his gravitational potential energy change during this climb?

Solution

The gravitation potential energy change is ΔU = mgh where m = mass of biker = 72 kg and h = vertical height of slope.

Since the angle of the slope is 4.3°, and the biker moves a distance of 1200 m along the road, the vertical height h he moves is gotten from

sin4.3° = h/1200

h = 1200sin4.3° = 90 m

So, ΔU = mgh = 72 × 9.8 × 90 = 63485 J = 63.49 kJ ≅ 63.5 kJ

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