1.

A student uses a simple pendulum of exactly 1 m length to determine g, the acceleration due to gravity. He uses a stop watch with the least count of 1 s for this and records 40 s for 20 oscillations. For this observation, which of the following statements is true?

Answer»

Error `DeltaT` in measuring T, the time PERIOD, is0.02 SECONDS.
Error `DeltaT`in measuring T, the time period, is 1 second
Percentage error in the deterinination ofg is 5%.
Percentage error in the determination of g is 2.5%.

Solution :Relative error in measurement of time,
`(Deltat)/t=(1s) /(40S)=1/40`
Time period , `T=(40 s)/20=2s`
Error in measurement of time period
`DeltaT=T xx (Deltat)/t= 2 s xx 1/40`= 0.05 s
The time period of simple PENDULUM is
`T=2pisqrt(l/g)` or `T^2=(4pi^2l)/g` or `g=(4pi^2l)/T^2`
`therefore (Deltag)/g=(2DELTAT)/T=2xx1/40 =1/20 (because (DeltaT)/T = (Deltat)/t)`
Percentage error in determination of g is
`(Deltag)/g xx 100=1/20 xx 100`=5%


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