# Quick banked curve help

1. Sep 25, 2007

### frasifrasi

we werre asked to draw the trajectory of the car going at maximum speed on a banked curve given the coefficient of kinetic friction. Since the friction equations are the same and I already calculated the maximum velocity allowed using the coefficient for static friction, should I just plug in this coefficient of kinetic friction in place of the old coefficient of static friction?

lastly, would it be right to set the path going toward the wall, and crasing like I imagine it to be?

2. Sep 25, 2007

### Staff: Mentor

Why would the car crash? The point of the banked curve and friction is that the car stays on the road without crashing. Kinetic friction is less than static friction, so it would be conservative use kinetic friction to determine maximum velocity if the wheels slipped. The wheels of a car rotate such that the tangential velocity of the surface of the tire matches the road speed of the vehicle. So the actual allowable maximum velocity would occur with static friction.

http://hyperphysics.phy-astr.gsu.edu/hbase/corf.html#cent

http://hyperphysics.phy-astr.gsu.edu/hbase/mechanics/carbank.html

3. Sep 25, 2007

### frasifrasi

so, can anyone suggest what would happen if the car was traveling at the maximum speed? would it go around the outside of the curve, almost touching the wall from beginning to end?

4. Sep 25, 2007

### frasifrasi

Actually, the question asks the motion of the car if it exceeds the maximum speed for the curve given a certain coefficient of sliding friction. Should it crash in this case?

5. Sep 25, 2007

### Staff: Mentor

If the car completely loses traction, it will travel tangent to the curve and hit the wall, which is occasionally what happens in autoraces like NASCAR and Indy 500.