- #1
spike spiegel
- 2
- 0
Homework Statement
This question relates centripetal acceleration and gravity. The general question is to determine the acceleration of gravity using centripetal force. A coin is tied to a string and swung in a circle over a person’s head. There is also a plastic tube attached to the string. The number of full rotations in a certain amount of time is counted, and the length of the string is measured as well. My question is, how would I go about finding the acceleration of gravity. I know that the centripetal force, (mv^2)/r, is equal to the force of gravity, F(g). I know the radius and the velocity, but what do I do for the mass, and how to I solve the overall problem for gravity? Is the mass just the mass of the coin, or the mass of the tube plus that of the coin?
Homework Equations
Centripetal force = (mv^2)/r
(mv^2)/r = F(c) = F(t) = F(g)
Mass of coin - 58.1 g
Mass of tube - 20.1 g
The Attempt at a Solution
One line of data
Using mass=coin + tube
20 revolutions in 18.91 s at a radius of 1.03 m
m = 58.1 + 20.1 = 78.2 g
r = 1.03 m
v = d/t
2pir = 2pi(1.03)/ 18.91 = 0.342 m/s
(78.2*.342^2)/1.03= 8.88 m/s^2
Pretty close to 9.8, but is this the right way to solve it?