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Delilah
Joined: 29 Mar 2010 Posts: 6 Location: Whiteville

Posted: Tue Mar 30, 2010 8:23 pm Post subject: Help Physics! 


A 1420kilogram car, moving with a speed of 15.0 m/s, is on a flat, circular curve having a radius of 50.2 meters.
How much friction is needed to keep the car on the road?___________N
What is the coefficient of friction between the tires and the road?_______ 

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hepcj Site Admin
Joined: 23 Jun 2007 Posts: 125

Posted: Tue Mar 30, 2010 10:29 pm Post subject: 


m =1420 kg
v= 15 m/s
r = 50.2
The force pushing the radially outward is
F = (m v^2)/r
= 1420 x (15^2)/50.2
= 6364.54 N
The car is kept on the track by the frictional force of the tyres opposing the centrifugal force F.
The frictional force is related to the weight by
F_fric = mu F_norm. where mu is the coefficient of friction.
Since the car is on a horizontal track, the magnitude of the normal force is:
F_norm = mg
1420 x 9.8 = 13916 N
Therefore, the coefficient of friction = 6364.54 N/13916 N = 0.46 

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Delilah
Joined: 29 Mar 2010 Posts: 6 Location: Whiteville

Posted: Wed Mar 31, 2010 1:35 am Post subject: 


thanks so much, im having a time trying to grasp Physics 

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