Energy Exchange in a Pendulum

Watch potential energy transform into kinetic energy and back again while total mechanical energy stays constant.

Period, T2.46 s
Angle, θ+25.0°
Speed, v0.00 m/s
Total energy, E1.37 J

Controls

1.50 m
The period remains about 2 s or longer.
0.50 kg
Mass scales the total energy — heavier bob stores more PE at the same height. Period is unaffected.
15°
Kept ≤ 20° so the small-angle approximation stays within ~2% error.
At an extreme position PE is maximum, KE is zero, and PE + KE still equals the same total energy.
Left extremePE = Total
KE = 0
EquilibriumKE = Total
PE ≈ 0
Right extremePE = Total
KE = 0
PE = mgh    |    KE = ½mv²    |    E = PE + KE = constant

Pendulum motion

left extreme equilibrium right extreme 0.5 kg h v
Total energy composition
PE 1.37 J + KE 0.00 J = Total 1.37 J
PE 100%
Potential energy Total bar always = 100% Kinetic energy

Individual energies

PE
1.37 J
KE
0.00 J
Total
1.37 J
potential energy kinetic energy total energy