Question

A 1480(k)g car pulls a 300(k)g trailer. The car exerts a horizontal force of 3900(N) against the ground in order to accelerate.

What force does the car exert on the trailer? Assume an effective friction coefficient of 0.15 for the trailer.

Answer 1

@mathmale can you please help me with this

Answer 2

@mathmale this is the problem

Answer 3

is this method correct:
1. get the friction on the truck and car
2. get the net force of the system
3. get the acceleration of the system
4. get the force on the truck.

Answer 4

It's been a while since I last tackled this sort of problem. My first thought was that we should draw a free body diagram for the trailer. Have you tried doing that?
But if we think about this further, that horizontal force of 3900 N causes BOTH car and trailer to move.

Answer 5

Would it make sense to calculate the acceleration of the car-trailer combination?
The friction force acts upon the trailer only, I believe. If you were to draw a free body diagram for the trailer alone, you'd need to show the unknown force, F, dragging the trailer to the right and the friction force Z, resisting the motion to the right (that is, pointing to the left).

Answer 6

The net force acting on the trailer is then F less Z, right?

Friction force Z is easy to calculate, since we know both the coefficient of dynamic friction (0.15) and the mass of the trailer (1480 Kg).
Think about this input for a while. Does it help? Are there gaps? What further need you to know to solve this problem?

Answer 7

At first glance, you mainly need to apply the F = m a formula. m is known. Is 'a' known?