- #1
smeiste
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Homework Statement
A pendulum consists of an object of mass m = 1.65 kg swinging on a massless string of length l. The object has a speed of 1.97 m/s when it passes through its lowest point. If the speed of the object is 0.87 m/s when the string is at 70° below the horizontal, what is the length of the string?
Correct answer: 2.64 m (to 3 sig figs)
Homework Equations
Ep = mgh
Ek = 1/2mv^2
The Attempt at a Solution
I tried the equation:
mg(length(1-cos20°)) = 1/2mv^2
and this did not work.. it worked when I had the length and needed the velocity?