# Centripetal Force Problem with Tension on an Unknown Planet

## Homework Statement

An experiment is conducted on a "strange" planet to determine the acceleration due to the force of gravity there. A 2 meter length pendulum is suspended and put into horizontal circular path. Data collected: the pendulum makes 10 revolutions in 25 seconds while sweeping out a circle of radius R=.209 meters.
Find "g" for this planet.

## Homework Equations

F = MA
Centripetal acceleration = V^2/R

## The Attempt at a Solution

V = 10(2πR)/25 = .53m/s
R = .209
X eq: TCos60 = m(V^2)/R
Y eq: TSin60 = mg (no acceleration in the y direction)

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kuruman
Homework Helper
Gold Member
So far so good. Can you find g from what you already have?
BTW, the units of V are not m/s^2, but that's a minor point.

So far so good. Can you find g from what you already have?
BTW, the units of V are not m/s^2, but that's a minor point.
I am having trouble solving this because there are three unknowns T, m, and g. I guess my algebra is rusty, or am I missing something? In other words, should I be able to solve this by system of equations at this point?

haruspex