The mass of a bicyclist and a bicycle together is 53.0 kg. How much work has been done if the bicyclist slows the bicycle from a speed of 3.84 m/s to 1.27 m/s?

Question

I'm not sure how to do this. I'm doing online school and I can't fully grasp this lesson

Answer 1

Algebraic sum of all the work is reflected as the change in kinetic energy.

Here Change in KE = .5(53.0)*(1.27)² - .5(53.0)*(3.84)² = -348.01 J

So the work done is -348J [ 3 significant figures ]

Note that the negative sign is consistent with that the work is done by friction and is negative as friction acts in the opposite direction of displacement.