Question

Consider four cases displaying the free-body diagram of a cyclist on a bicycle rolling Case A Case B down a hill (i.e., the cyclist is not peddling), as shown. Treat the cyclist and bike as a single mass and consider air resistance. Case C Case D frost back Select the free-body diagram that correctly displays the external forces acting on the cyclist and the bike. ○Case A ○Case B O Case C ○Case D

Answer 1

Option D will be the correct diagram. Weight of the system will act vertically downward. The reaction force will act upward along the Cos component of weight. This reaction force will be divide equally in two tyre along the centre of the tyre. Since the cycle is rolling down the friction between tyre and surface will act opposite to the motion . And the air drag F_air will act opposite and parallel to the motion. Thus the option D will satisfy.