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1D Dynamics Problem

  • Thread starter hydra03
  • Start date
  • #1
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1D Dynamics Problem!!!

Homework Statement


A car of mass 1100kg is traveling at a constant velocity of 60 km/hr, east. The coefficient of friction between the tires and the road is 0.45.
The driver of the car sees the traffic light in front turning red and steps on the brake, only to find that the brakes are not working. If the car is 35m before the intersection when this happens, would it be able to come to a stop before entering the intersection?


Homework Equations


F = ma
d = vt + 1/2at^2
vf^2 = vi^2 + 2ad
vf = vi + at

The Attempt at a Solution



I've fiddled around with the bottom three kinematic equations, but I don't seem to be getting anywhere..
 

Answers and Replies

  • #2
Dick
Science Advisor
Homework Helper
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Homework Statement


A car of mass 1100kg is traveling at a constant velocity of 60 km/hr, east. The coefficient of friction between the tires and the road is 0.45.
The driver of the car sees the traffic light in front turning red and steps on the brake, only to find that the brakes are not working. If the car is 35m before the intersection when this happens, would it be able to come to a stop before entering the intersection?


Homework Equations


F = ma
d = vt + 1/2at^2
vf^2 = vi^2 + 2ad
vf = vi + at

The Attempt at a Solution



I've fiddled around with the bottom three kinematic equations, but I don't seem to be getting anywhere..
It looks like you are supposed to assume the car is slowing down because of the 0.45 kinetic friction value. Start by trying to compute the acceleration a. To do that try to find the frictional force on the car first.
 

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