Calculate acceleration of object with applied force and friction

[username12345]

Homework Statement

A worker drags a crate across a factoryt floor by pulling on a rope tied to the crate. The worker exerts a force of 450 N on the rope, which is inclined 38 degrees to the horizontal, and the floor exerts a horizontal frictional force on 125 N that opposes the motion. You can assume the crate doesn't leave the ground.

Calculate the acceleration of the crate (mass = 310 kg).

Homework Equations

F = ma

The Attempt at a Solution

Broke the force of the pull into x and y components:

Fx = 450 cos 38 = 354 N
Fy = 450 sin 38 = 227 N

Then the friction opposes motion, so subtract that from the x component

Fx = 354 - 125 = 229 N

so the net force is \sqrt{229^2 + 227^2} = 322 N

then, a = \frac{F}{m} = \frac{322}{310} = 1.0 ms^{-2} to 2 s.f.

However the answer given is 0.74 ms

 

[Cyosis]

You're doing well until

so the net force is \sqrt{229^2 + 227^2} = 322 N

then, a = \frac{F}{m} = \frac{322}{310} = 1.0 ms^{-2} to 2 s.f.

However the answer given is 0.74 ms

The crate does not leave the ground so the only acceleration will be in the x-direction.

 

[username12345]

Ah, got it...

a = \frac{F_x}{m} = \frac{229}{310} = 0.74

Thanks.