Determination of Rigidity Modulus and Moment of Inertia
Mode Displacement = degree
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Procedure
First measure the time period of the empty cradle oscillation. In order to measure it, set a certain amount of angular displacement using the slider S2 (or the nearby textbox, e.g. 45 degree) and choose the mode Empty Cradle. After that, click on the Start button to start oscillation It also starts the timer (frame C).
Record the time taken for 20 (may be other number, but atlease 15 for better accurecy) complete cycle of oscillation in table I and calculate mean time period (T0) of oscillation from that.
The stopwatch (frame C) can be paused using the Stop button. This also pauses the motion of the cradle.
The entire experiment can be initiated using the Reset button. This also reset the timer to zero.
Similarly, measure the time periods (T1 and T2) for the "Cradle + Known body" mode and "Cradle + Unknown body" mode respectively. Record them in table I
Calculate the moment of inertia of the known body (Rectangular bar) using the equation,
where l (length) = 8.837 cm, b (breadth) = 2.543 cm and M (mass) = 420 gram.
Now estimate the moment of inertia of the unknown body (cylindrical) using the equation,
The unknown body is a cylinder in this case. It rotates about an axis passing through its centre of gravity and perpendicular to its length. It's mass is 0.0750717 gram, length is 10 cm and radius = 2 cm.
Calculate the moment of inertia theoretically (in this case) and compare with the experimental value.
If the radius(R) and the length(L) of the suspention wire is given, the regidity modulus of the of the material of the wire can be calculated from the equation
