We measure the period of oscillation of a simple pendulum. In successive measurements, the readings turn out to be $2.63 \;s , 2.56 \;s , 2.42\; s , 2.71 \;s$ and $2.80 \;s$. Calculate the absolute errors, relative error or percentage error.
Answer The mean perlod of oscillation of the pendulum
$T \;=\frac{(2.63+2.56+2.42+2.71+2.80) \,s}{5}$
$\quad=\frac{13.12}{5} \;s$
$=2.624\, s $
$=2.62 \,s$
As the periods are measured to a resolution of $0.01 \,s ,$ all times are to the second decimal; it is proper to put this mean perlod also to the second decimal.
The errors in the measurements are
$2.63 \,s -2.62 \,s =0.01 \,s$
$2.56 \,s-2.62 \,s=-0.06 \,s$
$2.42\, s -2.62\, s =-0.20 \,s$
$2.71 \,s -2.62\, s =0.09 \,s$
$2.80\, s-2.62\, s=0.18\, s$
The arthmetic mean of all the absolute errors (for arithmetic mean, we take only the magnitudes) is
$ \Delta T_{\text {mean}} =[(0.01+0.06+0.20+0.09+0.18) \,s ] / 5 $
$=0.54 \,s / 5 $
$=0.11 \,s $
$T=2.6 \pm 0.1 \,s$
$\delta a=\frac{0.1}{2.6} \times 100=4 \%$
If $Q= \frac{X^n}{Y^m}$ and $\Delta X$ is absolute error in the measurement of $X,$ $\Delta Y$ is absolute error in the measurement of $Y,$ then absolute error $\Delta Q$ in $Q$ is
A body travels uniformly a distance of $ (13.8 \pm 0.2)\,m$ in a time $(4.0 \pm 0.3)\, s$. The percentage error in velocity is ......... $\%$
A student uses a simple pendulum of exactly $1 \mathrm{~m}$ length to determine $\mathrm{g}$, the acceleration due to gravity. He uses a stop watch with the least count of $1 \mathrm{sec}$ for this and records $40$ seconds for $20$ oscillations. For this observation, which of the following statement$(s)$ is (are) true?
$(A)$ Error $\Delta T$ in measuring $T$, the time period, is $0.05$ seconds
$(B)$ Error $\Delta \mathrm{T}$ in measuring $\mathrm{T}$, the time period, is $1$ second
$(C)$ Percentage error in the determination of $g$ is $5 \%$
$(D)$ Percentage error in the determination of $g$ is $2.5 \%$
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The maximum percentage errors in the measurement of mass (M), radius (R) and angular velocity $(\omega)$ of a ring are $2 \%, 1 \%$ and $1 \%$ respectively, then find the maximum percenta? error in the measurement of its rotational kinetic energy $\left(K=\frac{1}{2} I \omega^{2}\right)$