# Vertical circular motion

1. Feb 4, 2012

### Nightrider00

1. The problem statement, all variables and given/known data

a piece of 4cm elastic stretches to 6.5cm when 100g mass is added. the same piece of elastic is now swung with constant angular velocity in the vertical circular direction.
find the length at the top and bottom of the circular motion when Time=0.2s

2. Relevant equations

3. The attempt at a solution

2. Feb 4, 2012

### tiny-tim

Welcome to PF!

Hi Nightrider00! Welcome to PF!

Show us what you've tried, and where you're stuck, and then we'll know how to help!

3. Feb 4, 2012

### Nightrider00

I am just confused whether the centripetal acceleration will be equal to the gravitational acceleration or not?

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Last edited: Feb 4, 2012
4. Feb 5, 2012

### tiny-tim

(just got up :zzz: …)
no …

almost everything in mechanics comes down to good ol' Newton's second law (F = ma) …

here, there are two forces (gravity and tension), and both must be put into the F = ma equation

5. Feb 5, 2012

### Nightrider00

So this is what i did... Is this okay

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6. Feb 6, 2012

### tiny-tim

(this is very difficult to read … can't you type it? )

no, the radius is not 6.5 cm

7. Feb 6, 2012

### Nightrider00

oh okay.. i get it nw.. thanks alot for the help..:-)