Question

The least count of a stop watch is ,(1/5)s. The time of 20 oscillations of a pendulum is measured
to be 25s. What is the maximum percentage error in this measurement?
1) 890
3) 0.8%
4) 16%​

Answer 1

Answer:

Number of oscillation =20

Total time taken for 20 oscillation =25 sec

Time period =25/20=1.25 sec

Least count of watch =0.2 sec

The measurement of time period 1.25 the measuring watch can measure upto 0.2 s thus the watch can measure 1.2 s but the uncertainity remains in the 0.05 s.

1.25 s=1.2+0.05

Thus, error =0.05 sec

Percentage error =(0.05/1.25)×100=4%