# A car goes around a vertical circle (Uniform Circular Motion)

1. Oct 30, 2009

### Chandasouk

1. The problem statement, all variables and given/known data

A small remote-control car with a mass of 1.51 kg moves at a constant speed of v = 12.0 m/s in a vertical circle inside a hollow metal cylinder that has a radius of 5.00 m.

What is the magnitude of the normal force exerted on the car by the walls of the cylinder at point A (at the bottom of the vertical circle)?

What is the magnitude of the normal force exerted on the car by the walls of the cylinder at point B (at the top of the vertical circle)?

Do I utilize Fnet = ma which would give me 43.488N as Fnet, but I do not see how that would help? I don't know what to do.

2. Oct 30, 2009

### tnutty

Try drawing a force diagram when the car in at the bottom of the cylinder and when its
at the top of the cylinder.

3. Oct 30, 2009

### Chandasouk

For Part A, it would just be Fn pointing up and w pointing down.

w=mg so (1.51kg)(-9.8) = -14.798N so Fn must be 14.798N ?

Would part B basically be the same?

4. Oct 30, 2009

### pr0blumz

F_y = m*a_y
a_y = v^2/r

Does that help?

5. Oct 30, 2009

### tnutty

For part A it should be N - mg = 0, right ? Since mg is pointing down thus N has to be
pointing up.

For part B its not quite the same.