Circular Motion: Ferris Wheel Dynamics

[Mehta29]

I'm on the right track, but I'm stuck here...

The radius of a Ferris wheel is 5 m and it makes one rev in 10 sec

a Find the difference b/w the apparent weight of a passenger at the highest and lowest points, expressed as a fraction of his weight, W

b What would the time for one rev be if teh apparent weight at the top were zero?
c What would be the apparent weight at the low point??

I have at the top that

mv^2/r = mg - Fn

and at the bottom

mv^2/r = Fn -mg

I really don't undestand what a is asking...(Fnbottom - Fntop)/ W ??

 

[OlderDan]

I really don't undestand what a is asking...(Fnbottom - Fntop)/ W ??

Yes you do. It's exactly what you said. Write your answer as Fnb - Fnt = _______W

 

[Mehta29]

but I am confused as if anything else would be needed...liek that blank befor e the W...would i need to expand any further or would i just keep it
Fnbottom - Fntop = xW

b would just be v^2/r = g? and then t = 2pir/v

and c would be Fnb = mv^2/r + mg...but how would i eliminate m?

 

[OlderDan]

but I am confused as if anything else would be needed...liek that blank befor e the W...would i need to expand any further or would i just keep it
Fnbottom - Fntop = xW

b would just be v^2/r = g? and then t = 2pir/v

and c would be Fnb = mv^2/r + mg...but how would i eliminate m?

Solve your earlier top and bottom equations for Fn. Take the difference between the two. Your result will be of the form
Fnb - Fnt = mA where A is a number that can be computed from the given information. You can do that. Once you have that form, multiply and divide by g
mA = mgA/g = WA/g
You can calculate A/g to express your answer as
Fnb - Fnt = (A/g)W with A/g replaced by a number.

 

[Mehta29]

i got A and B...but how would i manage part c?

im not seein anyway to cancel out the mass...

 

[OlderDan]

i got A and B...but how would i manage part c?

im not seein anyway to cancel out the mass...

What is your understanding of "apparent weight". All the forces in the problem are proportional to mass. It will cancel out.