Coefficient of Friction and Forces

[pippintook]

A flatbed tractor trailer takes off from a stop sign on a level road. If a box on the back slides back 10 meters while the truck goes forward 50 meters and attains a speed of 15 m/s, what is the coefficient of friction (μ) between the bed and the box? Assume the bed to be at least 10 meters long.


F_F= μF_N
F_N= mg


I don't know if those are the right formulas, specifically because no mass is given. I just don't know how to find the forces without acceleration; is there a formula for that? If these are the right formulas, how do I find the mass or F_N? I chose these formulas because F_F is the forward force, and it had μ in the equation. Help!

 

[LowlyPion]

That's some of them.

There is also F = m*a.

And that a would be really useful to know wouldn't it?

You know the final velocity and you know the distance, so you should be able to figure the "a" shouldn't you?

 

[pippintook]

Wow. Ok, so I've found "a", but still don't know how to get F_N, since I don't have the mass or force. I know there's some really obvious formula, but I CANNOT remember it.

 

[LowlyPion]

Wow. Ok, so I've found "a", but still don't know how to get F_N, since I don't have the mass or force. I know there's some really obvious formula, but I CANNOT remember it.

Maybe write out your equations and your mass will cancel out?

If you are looking for kinematic equations:
https://www.physicsforums.com/showpost.php?p=905663&postcount=2