A car (mass of 1700 kg) is parked on a road that rises 15 degrees above the horizontal. What are the magnitudes of (a) the normal force and (b) the frictional force that ground exerts on the tires?
(1.0 is the coeffeciant of static friction and 0.8 is the coefficent of kinetic friction between concrete and rubber)
ok now what????????????
2007-09-16 04:40:35 · 6 answers · asked by kwali 2 in Science & Mathematics ➔ Physics
Well you know that
Normal Force(N)=Mass(M) times force of gravity (g) times cos ()
So you can solve for the normal force using that equation
N=mg cos()
N=(9.8 m/s^2)(1700 kg) cos 15
N=16092.3 N(Newtons)
Also you know that
Frictional Force (FF)= coefficient of kinetic friction(u) times normal force (N)
Now you can solve for the frictional force
FF=uN
FF=(.8+1.0)(16092.3N)
FF=(1.8)(16092.3N)
FF=28966.2N
2007-09-16 04:54:17 · answer #1 · answered by smarty 1 · 0⤊ 0⤋
You'll only need the static friction since the car is not moving. Recall that the force exerted by friction is u*n, where u is the coefficient of friction and n is the normal force.
This is a general approach to *any* of these types of problems:
Draw a free-body diagram (all the forces with direction), then do Newton's 2nd law (add Forces in x-direction = m*a, same for y-direction). You will have 2 equations with 2 unknowns.
In this case, one of the unknowns is the normal force, the other the frictional force. Solve the equations and you're done.
2007-09-16 04:58:15 · answer #2 · answered by Dark Matter Physicist 3 · 0⤊ 0⤋
Although gravity acts straight down, the car is on a slope and tending to roll down ,so the force on the car has both horizontal and vertical components. The horizontal component will be the mass of the car times the sin of 15 degrees.
Since the car is not moving then the frictional forces are equal to the horizontal force (null acceleration)
2007-09-16 04:49:39 · answer #3 · answered by Anonymous · 0⤊ 0⤋
well this would be the point where i put the book down and say ***** it, maybe if my teacher wasn't such a retard i might know! but i'm a bad bad example!
at least you're taking the time to cheat! call a mate in your class, i'm sure someone can translate this jiberish into english!
2007-09-16 04:49:30 · answer #4 · answered by Anonymous · 0⤊ 0⤋
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2016-11-14 14:28:56 · answer #5 · answered by ? 4 · 0⤊ 0⤋
I'd suggest that you start remembering the trigonometry you didn't bother to learn in Trig. class because that is the --only-- thing that is going to save you now.
Doug
2007-09-16 04:45:45 · answer #6 · answered by doug_donaghue 7 · 0⤊ 0⤋