# Can't remember equation for coefficient

• Arwing
In summary, the conversation discussed a lab in class on calculating an unknown variable, possibly involving acceleration and the coefficient of friction. The other person in the conversation reminded the speaker of the definition of friction force and the need to create a free body diagram to find the necessary equations.

#### Arwing

Homework Statement
A crate rests on a flatbed truck which is initially traveling at 17.9 m/s on a level road. The driver applies the brakes and the truck is brought to a halt in a distance of 45.6 m. If the deceleration of the truck is constant, what is the minimum coefficient of friction between the crate and the truck that is required to keep the crate from sliding?
Relevant Equations
Fst=ma, Fn-Fg=ma
We did a lab in class on how to calculate it but he collected it and its days later, can't remember how to attempt it.

Hello @Arwing ,

Unfortunately we can't help if you don't post your attempt at solution (see guidelines).

However, you will need some more equations:
to relate the acceleration to initial speed and the distancce of 45.6 m​
to relate the coefficient of friction to some other variables in the problem.​

And: I have no idea what Fst is, or what Fn-Fg=ma means ...

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You don't need to remember anything. You have the definition of friction force available everywhere and you have to do a free body diagram to find the equations needed.

PhDeezNutz and hutchphd