In a simple pendulum experiment for determination of acceleration due to gravity $(g)$, time taken for $20$ oscillations is measured by using a watch of $1\, second$ least count. The mean value of time taken comes out to be $30\,s$. The length of pendulum is measured by using a meter scale of least count $1\, mm$ and the value obtained is $55.0\, cm$. The percentage error in the determination of $g$ is close to  ……….. $\%$

The most accurate reading of the length of a $6.28 \,cm$ long fibre is …………… $cm$

A set of defective observation of weights is used by a student to find the mass of an object using a physical balance. A large number of readings will reduce

The length of a cylinder is measured with a metre rod having least count $0.1 \;cm$. Its diameter is measured with vernier calipers having least count $0.01\; cm$. If the length and diameter of the cylinder are $5.0\; cm$ and $2.00\; cm$, respectively, then the percentage error in the calculated value of volume will be

In an experiment, mass of an object is measured by applying a known force on it, and then measuring its acceleration. If in the experiment, the measured values of applied force and the measured acceleration are $F=10.0 \pm 0.2 \,N$ and $a=1.00 \pm 0.01 \,m / s ^2$, respectively. Then, the mass of the object is …………… $kg$