Calculating Elastic Length in Vertical Circular Motion

[Nightrider00]

Homework Statement

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

Homework Equations

The Attempt at a Solution

 

[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!

 

[Nightrider00]

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

 

[tiny-tim]

(just got up :zzz: …)

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

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

 

[Nightrider00]

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

 

[tiny-tim]

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

no, the radius is not 6.5 cm

 

[Nightrider00]

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