(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

This should be an easy one. Please tell me what im missing.

A man is pushing a 75 kg crate at constant

velocity a distance of 12 m across a warehouse.

He is pushing with a force of 225 N at an angle

of 15° down from the horizontal. The coefficient

of friction between the crate and the floor is

0.24. How much work did the man do on the

crate?

Given - m=75kg, Δd=12m, Fa=225N [15° down from hor], μ=.24

2. Relevant equations

Ffriction = μ*Fn

W = F*Δd*cosθ

3. The attempt at a solution

First attempt

Ffriction = 176.4N

So

W = F*Δd*cosθ

W = (225 - 176.4)*12*cos15

W = 563.33N/m (wrong answer)

Second attempt

W = F*Δd*cosθ

W = 225*12*cos15

W = 2608N/m

W = F*Δd*cosθ

W = 176.4*12*cos180

W = -2116.8N/m

W = 2608 - 2116.8

W = 491.2N/m (wrong answer)

I've tried so many combinations I cant seem to figure it out. The answer is 320N/m btw

Please tell me what im doing wrong

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# Calculating work when 2 forces are present

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