A large pendulum suspended from the ceiling demonstrates conservation of energy by swinging out and back to its starting point near the instructor’s chin, never exceeding its original height. The dramatic demonstration shows that mechanical energy is conserved and that potential energy converts to kinetic energy and back.

1. Suspend a large pendulum from the ceiling of the lecture hall.
2. Position a ladder with a plywood backdrop behind the instructor.
3. The instructor holds the pendulum bob against their chin while standing against the plywood.
4. Without giving the pendulum any push, release it and allow it to swing across the room.
5. Observe as the pendulum returns to its original position, stopping just short of the instructor’s chin.
6. To surprise students, subtly push the pendulum during a first trial so it strikes the plywood backdrop on return.

Conservation of Energy - Best demonstration Ever !! - The PhysicsMaths Wizard:

When a physics teacher knows his stuff !! - Lectures by Walter Lewin:

📄 Giant Pendulum - Stony Brook University: https://labdemos.physics.sunysb.edu/c.-kinematics-and-dynamics/c8.-mechanical-energy-and-power/giant-pendulum

• Use a smaller pendulum version for classroom demonstrations.
• Record the motion with a slow-motion camera to analyze speed changes.
• Have a second person mark the maximum swing heights to show that the pendulum never exceeds its starting position.

• Only the instructor should stand in front of the pendulum; students must stay back.
• Do not give the pendulum any forward push if it is released near the face.
• Ensure the pendulum is securely attached to the ceiling before use.
• Always stand with your back against the plywood so you cannot lean forward accidentally.

• Why does the pendulum bob not hit the instructor on its return swing? (It cannot rise higher than its initial height due to conservation of energy.)
• What forms of energy are being exchanged during the pendulum’s motion? (Potential energy at the highest points and kinetic energy at the lowest point.)
• What would happen if the pendulum were given an initial push instead of just being released? (It would return with extra speed and could rise higher, making the demonstration unsafe.)