Friction compared to applied force

[Shanetm]

Homework Statement

I am doing review questions about friction and am I little confused about the one I am currently doing. I have an idea of what the answer is but i want to be positive.

The question asks to compare friction to applied force of an object on a horzontal surface. Compare them when the object is slowing down, travelling at a constant velocity and speeding up

The Attempt at a Solution

I have the answers as both will decrease, both will stay the same and both will increase but I feel like this may not be correct. Help would be appreciated.

 

[BruceW]

Well the friction is usually modelled as a function of speed (either linear or as speed squared). So you are right about how friction will act in those situations.

But the applied force is a bit more complicated. I think you'd need to write down a model of the friction force and the applied force and work it out. (In other words, I don't think there is a general answer)