The discussion revolves around calculating the tension between a car and a trailer, focusing on the forces acting on both the car and the trailer. Participants explore concepts related to free body diagrams and force balance equations within the context of dynamics.
Some participants have provided guidance on drawing free body diagrams and identifying forces, while others express confusion about specific aspects of the problem. There is an ongoing exploration of the forces acting on the trailer and the importance of friction in the context of the car's movement.
Participants note that the trailer's tires are not driven, leading to discussions about the relevance of friction in this scenario. There is also mention of the time taken for the car to reach a certain speed, which may influence the understanding of the forces involved.
It is unnecessary to include a friction arrow for the trailer because its tires are not driven; they are just idling. But including a friction arrow for the force the road exerts on the car is important. Which direction do you think this arrow is pointing?Thomas Hochkins said:
A car engine is not a jet engine. If there were no friction between tyres and road, would the car go?Thomas Hochkins said:
This is not correct. As haruspex was alluding to in the previous post, the frictional force exerted by the road on the car tires is pointing forwards, in the direction that the car is moving. The tires are driven by the car engine, and they are pushing backwards on the road surface. The road surface, in turn, is pushing forward on the car. This is where haruspex was saying that the forward arrow should go.Thomas Hochkins said: