Torsional oscillations
If an object of moment of inertia I is hung from the lower end of a
torsion wire of length L, radius r and modulus of rigidity (shear modulus) G (Figure 1); then
the period is given by:
Torsional oscillations:
Period (T) = 2p[2IL/Gr]1/2
Student investigation
This investigation is based on the centre of percussion of an object.
Suspend a metre ruler by hanging it on a matchstick passed through a hole at the 5 cm mark. Now strike the ruler a sharp blow with a hammer two thirds of the way down. What happens to the matchstick?
Now try hitting it at other points.
Find out why this experiment gives the results that it does.
How do the results apply to ball games such as rounders, baseball and cricket?
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