- #1
PhysicsCollegeGirl
- 6
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1. Homework Statement
An amusement park ride consists of a large vertical cylinder that spins about its axis fast enough that any person inside is held up against the wall when the floor drops away (see figure). The coefficient of static friction between person and wall is μs, and the radius of the cylinder is R.
Homework Equations
1. Show that the maximum period of revolution necessary to keep the person from falling is T = (4π2Rμs/g)1/2
2. If the rate of revolution of the cylinder is made to be somewhat larger, what happens to the magnitude of each one of the forces acting on the person? (Select all that apply.)
a. The normal force remains the same.
b. The gravitational force remains the same and the frictional force increases.
c. The gravitational force and frictional force remain constant.
d. The normal force increases.
3. If the rate of revolution of the cylinder is instead made to be somewhat smaller, what happens to the magnitude of each one of the forces acting on the person? (Select all that apply.)
a. All the forces decrease.
b. The gravitational force remains constant.
c. The gravitational force decreases.
d. The normal and frictional force decrease.
The Attempt at a Solution
I already got the right answers, but mostly with trial and error. In the 2nd question the answer are: c & d; and for the 3rd question the answers are b & d.
So, now I am confused. How come when the period is larger, the gravitational force remains constant, along with the friction, but when it gets smaller the normal and friction decrease. What I am trying to say is that I see the relationship between normal force and friction, so why doesn't friction increase when normal force increases in the first scenario. I am just trying to get my head around it. Thanks!