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

A 2.1x10^3 kg car starts from rest at the top of a driveway that is sloped at an angle of 20 degrees with the horizontal. An average friction force of 4x10^3 N impedes the car's motion so that the car's speed at the bottom of the driveway is 3.8 m/s. What is the length of the driveway?

2. Relevant equations

mass of car =2.1x10^3 kg

velocity (final)=3.8 m/s

average friction force= 4x10^3

driveway sloped at 20 degrees

kinetic energy theorem=1/2m(vf)^2-1/2m(vi)^2

work formula=fd(cos θ)

w=ke

3. The attempt at a solution

If I log the numbers into the kinetic theorem equation

ke=1/2(2.1x10^30)(3.8m/s)^2

If I log the numbers into the work equation

w=4x10^3d(cos 20)

and ke=w

doesn't 4x10^3d(cos 20)=1/2(2.1x10^30)(3.8m/s)^2?

If I simplify this, the distance is 4.03. Is there anything wrong with my equation?

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# Homework Help: Work and kinetic theorem problem using friction

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