Least count of a stopwatch is 1/5 s. The measured time of 20 pendulum oscillations is 25 s. Maximum percentage error in the period is 0.4k%. Find k.
Physics · Mixed Chapter
JEE Main Practice

Question

Least count of a stopwatch is 1/5 s. The measured time of 20 pendulum oscillations is 25 s. Maximum percentage error in the period is 0.4k%. Find k.

G1 Physics · Accepted Answer

Step 1: Time period T=t/20, so relative error ΔT/T equals Δt/t (number 20 exact). Step 2: Maximum percentage error = (0.2/25)×100 = 0.8%. Step 3: 0.8%=0.4k% ⇒k=2.