# Homework Help: Help with physics lab containing the centripetal acceleration law

1. Aug 25, 2010

### funkimunkeyy

1. The aim of the lab is to verify the centripetal acceleration law which states that acceleration is equal to the velocity squared divided by the radius. During the lab, we spun a
string powered whirligig. There was a ball at the top, attached to string, the string was threaded through a plastic tube which served as a handle, and there was a metal weight attached to the bottom. The purpose of the lab was to calculate centripetal acceleration and acceleration of the metal weight. I'm not sure if the the acceleration of the weight is acceleration due to gravity though and may need some clarification.

2. these are some of the equations used: a= v squared/ r, pi x d, a= f/m

3. I have managed to work out the centripetal acceleration, but not the acceleration of the metal weight. I know the two accelerations are somehow related, as the acceleration of the metal weight involves gravity, but i'm stuck. please help

2. Aug 25, 2010

### kuruman

Did the metal weight accelerate? If so, how?

3. Aug 25, 2010

### funkimunkeyy

yes, the metal weight did accelerate, but i worked out the acceleration by dividing the force on the metal weight by the mass of the ball

4. Aug 25, 2010

### kuruman

Are you saying that the metal weight moved and as it moved its velocity was changing?
And what number did you get when you did that? What was the force on the metal weight?

5. Aug 27, 2010

### funkimunkeyy

I got 27.9m/s^2 for the acceleration. The force on the metal weight was a tension force

6. Aug 27, 2010

### kuruman

How did you get this number? It is almost three times the acceleration of gravity. Can a hanging mass accelerate more than the acceleration of gravity? I don't think so. The best it can do is 9.8 m/s2 and that's when it is in free fall.

Also, you did not answer my other question, "Did the hanging mass move and did its velocity change as it did so?"

7. Aug 27, 2010

### funkimunkeyy

the acceleration was a centripetal acceleration. yes it moved and it's velocity changed

8. Aug 27, 2010

### kuruman

Did the hanging metal weight go around in a circle? If so, how did you calculate its acceleration? Please show your work.