Boxi Learn › Physics › Stage 4 · Systems and Argument
What sets a pendulum's beat?
PHY-2 Energy and momentum are conservedPHY-4 Waves carry energy, not stuffX-1 Guess, then check
What many people think
A heavier bob swings slower.
The idea
For small swings the period depends only on the length (T = 2π√(L/g)); height energy and speed energy keep trading places.
Explain it
A grandfather clock runs slow. Should you move the bob up or down the rod, and would a heavier bob help? Explain using T = 2π√(L/g).
Try at home
Tie a key to a 1 m string and time 10 swings; repeat with two keys, then with the string 25 cm long. Which change matters, and by how much?