alleryStart learning →A pendulum of mass m swings to amplitude angle θ. At the lowest point of swing, the TENSION in the string equals:
- mg
- mg(2 − cos θ)
- mg(3 − 2cos θ)
- 2mg sin θ
Show answer and solution
Correct answer: C. mg(3 − 2cos θ)
**At the lowest point:** T − mg = mv²/L (centripetal).
v² at bottom = 2gL(1 − cos θ) (energy conservation from amplitude).
We have So T = mg + 2mg(1 − cos θ).
So So T = mg(3 − 2cos θ).
For θ = 60°: T = mg(3 − 1) = 2mg.