Max Speed Calculation for a 1600 kg PT Cruiser on a 50m Radius Road

AI Thread Summary
To determine the maximum speed of a 1600 kg PT Cruiser on a 50m radius road with a static friction coefficient of 0.80, the centripetal force must equal the maximum frictional force to prevent skidding. The equation used suggests that mass cancels out, indicating that the maximum speed is independent of the car's mass. The correct maximum speed is calculated to be approximately 19.8 m/s, contrary to the provided answer of 6.3 m/s, which is deemed incorrect due to a potential oversight in calculations. A free-body diagram is recommended for better understanding of the forces at play. The discussion emphasizes the importance of correctly applying physics principles to solve the problem.
jtm
Messages
19
Reaction score
0
This problem I have to do is really bothering me.

Your 1600 kg PT Cruiser moves around a level 50m radius road. The coefficient of STATIC friction between the car tires and the road is 0.80. Determine the MAX speed of the car so that it does not skid off the road.


I think I get somewhere around.

ma - mg*0.80 = mv^2 / R I'm sure this is wrong because m shouldn't be able to be cancelled. Always ALL the information provided is used in the calculation.
 
Physics news on Phys.org
jtm,

m shouldn't be able to be cancelled.

Why not?
 
Always ALL the information provided is used in the calculation.

Also, it gives the wrong answer ;) I checked.
 
jtm said:
This problem I have to do is really bothering me.
Your 1600 kg PT Cruiser moves around a level 50m radius road. The coefficient of STATIC friction between the car tires and the road is 0.80. Determine the MAX speed of the car so that it does not skid off the road.
I think I get somewhere around.
ma - mg*0.80 = mv^2 / R I'm sure this is wrong because m shouldn't be able to be cancelled. Always ALL the information provided is used in the calculation.
1. What is 'a' ?
2. The answer is independent of the mass, m.
 
Answer from what I have on key is 6.3 m/s I am getting 19.8 m/s with mass cancelling out. We don't have a :) I'm assuming 0.
 
Think about this one physically first. If the car is going in a curve, there must be a centripetal force acting. Where is that force coming from? What you're looking for is the speed at which the maximum value of the force providing the centripetal force is exactly what's necessary to hold the car on the road. If it goes any faster, that force will not be able to hold it, and the car will skid.

So - at the point in which you're interested, the centripetal force must equal the maximum of the force providing it. You'll find the masses do cancel out. Sometimes teachers will give you information you don't need, to see if you'll find a way to stick it in anyway. I speak from experience.
 
jtm said:
Answer from what I have on key is 6.3 m/s I am getting 19.8 m/s with mass cancelling out. We don't have a :) I'm assuming 0.
19.8 m/s is correct. The key is wrong. They forgot to multiply by 'g' !

PS : Did you draw a free-body diagram ?
 
Back
Top