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## Homework Statement

*A pendulum with a swing amplitude of 150 cm is recorded to have a period of 2.1s. Calculate after 0.3s release from the furthest amplitude position.*

a) Angular velocity

b) displacement

c) Angular acceleration

d) Length of the pendulum

a) Angular velocity

b) displacement

c) Angular acceleration

d) Length of the pendulum

I've only had one lecture on circular motion and the motion of pendulums, so I'm a bit unsure of the correct steps for each calculation.

## Homework Equations

[tex]\omega = \frac{2\pi}{T}[/tex]

[tex]x = A cos (\omega t)[/tex]

[tex]a = -\omega^{2}x[/tex]

[tex]T = 2\pi\sqrt{\frac{l}{g}}[/tex]

## The Attempt at a Solution

a)

[tex]\omega = \frac{2\pi}{2.1} = 2.99 rad s^{-1}[/tex]

b)

[tex]x = 1.5 cos (2.99 x 0.3) = 1.5 m[/tex]

c)

[tex]a = -(2.99)^{2} x 1.5 = -13.41[/tex]

d)

[tex]l = \frac{T^{2}g}{2\pi^{2}} = 106.74 m[/tex]

I'm not convinced that I'm getting b) right, as it seems odd for the displacement after 0.3 seconds to be the same as the amplitude. This makes me believe that I'm wrong in other places.

See whats wrong? [I dont have the answers to check for myself]

Any similar problems to practice on would be welcomed; I don't want to constantly feel that I'm missing something.