(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

You take a bathroom scale onto a stand-up rollercoaster (the riders are always in a standing position). Before the ride

starts, you stand on the scale and note that it reads 65 kg. The ride starts and at the top of the first loop you are upsidedown and your scale reads 77 kg. You estimate that the loop has a radius of 15 m. How fast were you going at the top

of the loop?

2. Relevant equations

Fn = reading of scale

Fg = mg

ac = v^2/r

3. The attempt at a solution

I drew a FBD where the normal force and the force of gravity both point downwards towards the centre of the circle. The centripetal force equals the sum of the normal force and the force of gravity:

Fc = Fn + Fg

The problem is that I don't know what Fn is. Is it (77kg)(9.8N/kg)? If this is the case, I would then do:

Fc = (77kg)(9.8N/kg) + (9.8)(65)

I would then divide this value by 65 to get the centripetal acceleration (21.4 m/s^2).

I would then plug 21.4 m/s^2 into the equation ac = v^2/r and solve for v (about 17.9 m/s)

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# Homework Help: Scale on Top of Rollercoaster

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