Why does a pendulum eventually stop?
Show answer & explanation
Answer: Air resistance and friction
String stretches over time — Wrong. String stretch is minimal. Pendulum stops because air resistance and friction convert kinetic energy to heat.
Weight becomes lighter — Wrong. Weight doesn't change. Energy dissipates through air resistance and friction at pivot point, gradually stopping pendulum.
Air resistance and friction ✓ — Correct! Ideal pendulum (no friction/air resistance) swings forever—conservation of energy. Real pendulums lose energy: (1) Air resistance—pendulum pushes air molecules, loses kinetic energy to heat. (2) Pivot friction—bearing resistance. Energy converts to heat. Amplitude decreases each swing—damped oscillation. Eventually stops. Grandfather clocks have weights/springs adding energy to compensate losses. Vacuum + frictionless bearing = pendulum swings for days!
More Physics in Daily Life questions
- In a warm office that already reads 26 C, which change can make people feel cooler without lowering the thermostat?
- Why might 26 C feel acceptable in a breezy naturally ventilated summer building but too warm in a sealed winter office?
- On a warm humid day, why can the same 27 C room feel much worse once you start sweating?
- Why can moving air make a 27 C room feel cooler without changing the thermometer?
- Which hidden factor can make a desk beside a cold window feel chilly even when the thermostat across the room still reads 22 C?
- In the same 22 C room, why might someone who just climbed stairs feel warm while someone sitting in a T-shirt feels chilly?