Question

A child is pedaling such that a force of 51 N is exerted on him and his bicycle in the forward direction (F1). However, the air is exerting a drag force of 5 N in the opposite direction (F2). A force diagram for this situation (including a red velocity arrow) is shown to the right. If the mass of him is 25 kg and and that of his bicycle is 8 kg, what would his acceleration be?

Answer 1

Any idea on how to do this?

Answer 2

@matt101

Answer 3

Use F=ma.

Note that this equation uses the NET force (which you can find from the information in the question) and you need to consider the TOTAL mass of the child and their bicycle.

Answer 4

Thanks!