# Max. speed you can drive on a circular hill an still be in Uniform Circular Motion

Max. speed you can drive on a circular hill an still be in "Uniform Circular Motion"

## Homework Statement

The top of a hill is in the shape of a circle of radius 25 meters.

## Homework Equations

a) What is the normal force that the road exerts on an 1800kg car as it tops the hill with a speed of 8.0 m/s?

b) At what speed would the driver experience a moment of weightlessness as they top the hill?

## The Attempt at a Solution

My question isn't about performing calculations, I just wanted to make sure I am understanding the concept.

In part b, if the driver is experiencing weightlessness, is it correct to say that the car has exceeded the maximum speed that you can have on the hill and still be in "Uniform Circular Motion"? If that's the case then there is no normal force on the car at that point?

rock.freak667
Homework Helper

In part b, if the driver is experiencing weightlessness, is it correct to say that the car has exceeded the maximum speed that you can have on the hill and still be in "Uniform Circular Motion"? If that's the case then there is no normal force on the car at that point?

Yes that is correct. During normal circular motion, the normal force would be the force that the driver experiences, so if he is weightless then the normal force is zero.

PeterO
Homework Helper

## Homework Statement

The top of a hill is in the shape of a circle of radius 25 meters.

## Homework Equations

a) What is the normal force that the road exerts on an 1800kg car as it tops the hill with a speed of 8.0 m/s?

b) At what speed would the driver experience a moment of weightlessness as they top the hill?

## The Attempt at a Solution

My question isn't about performing calculations, I just wanted to make sure I am understanding the concept.

In part b, if the driver is experiencing weightlessness, is it correct to say that the car has exceeded the maximum speed that you can have on the hill and still be in "Uniform Circular Motion"? If that's the case then there is no normal force on the car at that point?

DOn't forget that when you have calculated a speed for part (b), you answer is likely to be "At least a speed of .... "