Question from Jessie, a student: In a "Rotor-ride" at a carnival, world are rotated in a cylindrically walled "room". The room radius is 4.6m and also the rotation frequency is 0.550 changes per second as soon as the floor drops out. What is the minimum coeffective of static friction so that world will certainly not slip down? People on this ride say they were "pressed versus the wall". Is there really an outside force pushing them against the wall? If so, what is its source? If not, what is the correct description of their instance (besides scary)?

Hi Jessie.

You are watching: In a rotor ride at a carnival

There is no pressure pressing them versus the wall. The pressures associated are:

1. gravity (acting downwards of course), 2. friction (counteracting gravity) 3. centripetal pressure of rotation (acting from the center of the cylinder into the wevery one of the cylinder) 4. normal force (counteracting the centripetal force)

The force of gravity is ssuggest (mg). In order for the friction to be enough to save a person from falling, the frictional force must be (-mg).

Frictional pressure for an object at rest (static friction) is FN where μ is the co-effective of static friction and N is the normal pressure from the wall towards the perboy. Therefore, μ=F/N. But F=mg, so μ=mg/N.

The magnitude of the normal force is ssuggest the same as the centripetal pressure bereason you don"t fall through or lift off the side of the cylinder. Centripetal force is calculated as F=ma where a is the centripetal acceleration. So μ = mg / N = mg / ma = g / a.

However before, centripetal acceleration is a=v2/r where v is the tangential velocity and also r is the radius of the cylinder. The tangential velocity is vr, wright here ω is the angular velocity in radians per unit time. Hence μ= g / a = g / (rω2).

Now you have an equation for the coreliable of static friction (μ) in regards to the radius (r) and also the angular velocity (ω), which you know.

You"ll need to transform your angular velocity from changes per second to radians per second before substituting for g, r and also ω.

Hope this helps, Stephen La Rocque.

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