# Homework Help: Angular vs Radial Acceleration

1. Apr 17, 2015

### DaveTan

1. The problem statement, all variables and given/known data
The cosmoclock 21 Ferris Wheel in Yokohama City, Japan, has a diameter of 100m. Its name comes from its 60 arms, each of which can function as a second hand (so it makes one revolution every 60.0s).

a) Find the speed of the passengers when the Ferris wheel is rotating at this rate [No problem]
b) A passenger weighs 882N at the weight-guessing booth on the ground. What is his apparent weight at the lowest point of the ferris wheel?

2. Relevant equations
d = vt
w = mg

3. The attempt at a solution
I have no problem with part a.

distance = 2pi r = 314.1m
velocity = 314.1/60 = 5.235m/s

It is part b where I get confused. I get it right till the step to use acceleration. I use radial acceleration and get it wrong, googled the question and someone used angular acceleration. I used his angular acceleration value and my answer was correct. But I am wondering why use angular acceleration instead of radial?

Weight on ground = 882N
Mass = 89.9 kg

F = ma
Nb - mg = ma
Nb = m (a +g)

*This is the part where I use radial acceleration
a = v2/r
a = 0.1745m/s2

Nb = 89.9 (0.1745+9.81)
Nb = 897.6N

2. Apr 17, 2015

### BruceW

Hi, welcome to physicsforums :)
the equation you are using a=v2/r is the correct one. And your value for the velocity is good. I think you made a mistake in doing the calculation v2/r. what values did you use? Remember you should be using radius, not diameter.

3. Apr 17, 2015

### DaveTan

Hey Bruce! Haha you are right! Opps!! Thank you!

4. Apr 17, 2015