Question

Is this possible to solve? A carnival ride where you stand up against the wall and after the ride starts spinning the floor drops out from under the rider has a 2.0 m radius and rotates 1.1 times per second. When the floor drops down, riders are held up by friction.
What coefficient of friction is needed to keep the riders from slipping?

Answer 1

It seems like you would need to know the mass.

Answer 2

I believe it is possible if you know the centripetal force

Answer 3

oh, so your question is if there is enough information to solve the problem?

Answer 4

Yes. It seems like it is not possible.

Answer 5

is this from a textbook? and is it the full question?

Answer 6

It is from a review my teacher put together ( the irony). All that I did not mention is (Friction is the force that hold the riders against the wall and the centripetal force keeps them from flying).

Answer 7

ok, i know you can get the velocity, you know the radius...

Answer 8

The velocity is 14 m/s tangent to the circle and the Centripetal Acceleration is 95 m/s^2 towards the center. This is where I get stuck, what should I do next?

Answer 9

Based on the formulas I have, I would need mass to find the centripetal force. Fg=Fnorm but you would still need MxA=Fg.

Answer 10

consequently those are for translational motion; let me thin

Answer 11

think*

Answer 12

We need some more people in here to help.

Answer 13

@LastDayWork

Answer 14

@petiteme

Answer 15

I think there is not enough info. What do you think @petiteme @LastDayWork@roadjester

Answer 16

@zepdrix Do you think you can help me?

Answer 17

@ajprincess Do you think you can help me?

Answer 18

Am sry. no idea.

Answer 19

Thanks for the help anyways @ajprincess

Answer 20

@Mashy Are you up for the challenge?

Answer 21

well.. i got 5 minutes before my meal is served.. lets see if i can understand this :P

Answer 22

@UnknownRandom g'night man

Answer 23

Good night @roadjester it was nice meeting you!

Answer 24

i don't understand the quesiton.. what do you mean, the floor DROPS? o.O

Answer 25

Its a ride that spins in a circle and at a certain point the floor drops from underneath your feet while you are spinning.

Answer 26

*It's

Answer 27

ohww.. so you keep spinning eh?..
and the centrifugal force on you makes the normal force huge enough, for the frictional force to counter your weight? is that right?

Answer 28

Yes indeed it is really awesome.

Answer 29

thats called tunnel of death :D..

Answer 30

i have even seen it.. cars and motorcyclists doing that :D..ok ok so whats the problem now?

Answer 31

What coefficient of friction is needed to keep the riders spinning?

Answer 32

ok

centrepetal force = Normal force

and friction should be equal to weight

hence (mu)(N) = mg
or
(mu) (v^2/R) = g

since all the stuff is mentioned.. u can calculate the mu right?

Answer 33

so thats the min value of mu!

Answer 34

The problem is I wasn't given a mass. That is why I was thinking the problem isn't solvable.

Answer 35

Well.. mass doesn't come into picture :D

it maybe not so intuitive.. but u see.. MORE mass gives more weight.. and so you may think.. HEY mass must be in the picture..
but wait.. more Mass also means more Centripetal force, and thus more Friction..
so they cancel

most of the cases in friction, you ll see masses cancel out

another class example is the stopping distance of vehicle when braked.. INDEPENDENT of mass only depends on mu

also the max angle to which you can make a slope, before an object starts sliding also INDEPENDENT of mass.. only depends on mu!