# Coefficient of friction (between road and wheels of accelerating truck)

## Homework Statement

What is the coefficient of friction between the road and the wheels of a 1400kg truck accelerating at 2 m/s/s if the force applied by the engine to the wheels is 4000N.

Fn = m * g
Ff = mu * Fn

## The Attempt at a Solution

I do not know how to resolve this as I don't know Ff or mu (i.e. two variables)
Any asisstance (not answer) would be appreciated.

## The Attempt at a Solution

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rock.freak667
Homework Helper
First draw a free body diagram.

Then find the resultant force in the horizontal (x) direction.

Newton's 2nd Law states that ∑Fx= ma

thanks rock.freak667,
I have found the answer it was on a website called http://www.physics247.com/physics-homework-help/friction-and-weight.php" [Broken] the answer was 0.09 as is shown here:

mu = Ff/Fn
Ff = (ma) - Fengine
mu = ((ma) - Fengine)/-(mg)
mu = ((1400 * 2) - 4000)/-(1400 * 9.81)
mu = (2800 - 4000)/-13734
mu = -1200/-13734
mu = 0.085...
mu = 0.09

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rock.freak667
Homework Helper
Once you understand the thinking process, as that will allow you do similar problems or slightly more complex ones.