- #1
princesspriya
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Homework Statement
a 2.1*10^3 kg car starts from rest at the top of a driveway that is sloped at an angle of 20 with the horizontal. An average friction force of 4.0*10^3 N impedes the car's motion so that the car's speed at the bottom of the driveway is 3.8m/s., What is the length of the driveway?
Homework Equations
The Attempt at a Solution
Ff=4000N
2100 Kg
X=20 degrees
Vf=3.8 m/s
Vi=0 m/s
Wnet=1/2MVf^2-1/2MVi^2
Wnet= 1/2*2000*3.8^2
Wnet= 15162 N
Wnet = FfdcosX
15162=4000cos20D
D=4.03m
but the book says 5.1m?
i can't figure out what i did wrong
thx for the help.