Probably to be more accurate. With hand-operated stop watches there is more room for (human) error.
Answer:
In a controlled experiment, an independent variable (the cause) is systematically manipulated and the dependent variable (the effect) is measured; any extraneous variables are controlled. The researcher can operationalize (i.e. define) the variables being studied so they can be objectivity measured.
Using the Universal Gratitation Law, we have:
Again applying the formula in the new situation, comes:
Number 4If you notice any mistake in my english, please let me know, because i am not native.
The equivalent of the Newton's second law for rotational motions is:

where

is the net torque acting on the object

is its moment of inertia

is the angular acceleration of the object.
Re-arranging the formula, we get

and since we know the net torque acting on the (vase+potter's wheel) system,

, and its angular acceleration,

, we can calculate the moment of inertia of the system: