# What is the magnitude of the frictional force acting on the crate?

## Homework Statement

A crate with a total mass of 50 kg is initially at rest on a level floor. A horizontal force of 150N pushes the crate across the floor at a constant acceleration of 1.2m/s2. What is the magnitude of the frictional force acting on the crate?

## The Attempt at a Solution

So this question seems so basic but I know I'm doing it wrong. All i did was plugged the numbers into the F=$$\mu$$N formulas and got $$\mu$$= .31. But in using that formula I am not even taking into account the acceleration and I dont know what to use in order to take it into account?! Someone please explain

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It's just F=ma on the crate, but remembering that there are 2 forces acting here; the 150N and the friction.

It means that if 50N force is foreword,then frictional force must act backward.
let net force be fn.
so according to the free body diagram,
fn=150-f (say frictional force be f) ........1

fn=ma=50*1.2
Now from this you'll get fn & from equation 1, you'll get f.