Question

The following measurements for the pendulum has been record in the table below:

Mass of bob	58.10 g	0.05810 kg
Diameter of bob	2.00 cm	0.0200 m
Hight of bob at rest above table	9.00 cm	0.0900 m

You measured the time it takes for the bob to pass through the photogate for 3 trials at two different release heights. Pull back the pendulum and measure the height of the bob above the table using a ruler. Try to keep the height of the bob the same for each of the three trials. Reset the timer between trials.

Release Height	Time: Trial 1	Time: Trial 2	Time: Trial3	Average
30.0 cm	0.0110 sec	0.0090 sec	0.0100 sec
15.0 cm	0.01870 sec	0.01850 sec	0.01830

How much higher (vertically) is the pendulum at each release height than it was when it was hanging at rest? Convert this distance to meters and calculate the gravitational potential energy, GPE, of the bob.

Release Hight	h	Potential Energy (Joules)
30.0 cm
15.0 cm

Calculate the velocity of bob at the bottom of the swing:

diameter of bob (m) / average time (sec) = speed of bob (m / s )

Release Height	Speed of bob (m/s)	Kinetic Energy of the bob at the bottom of the swing
30.0 cm
15.0 cm

Compare the values for the gravitational potential energy and kinetic energy of the pendulum. Was energy conserved, that is, were they equal? If not, how might you account for the difference in energies?

Answer 1

And for this (g)effective the GPE will equal to Kinetic energy of bob at the bottom..

therefore energy will be conserved.