Question

The time taken to complete $20$ oscillations by a seconds pendulum is:

• A. $20s$
• B. $50s$
• C. $40s$
• D. $5s$

Answer 1

The correct option is C $40s$

We know that the time period of a seconds pendulum is $T=2$ sec. One second for a swing in one direction and one second for the return swing.

Thus, time taken to complete one oscillation is $2$ sec.

Hence, time taken to complete 20 oscillations is $2\times 20=40$ sec.