The distance $s$ travelled by a particle in time $t$ is $s=u t-\frac{1}{2} \,g t^{2}$. The initial velocity of the particle was measured to be $u=1.11 \pm 0.01 \,m / s$ and the time interval of the experiment was $t=1.01 \pm 0.1 \,s$. The acceleration was taken to be $g=9.8 \pm 0.1 \,m / s ^{2}$. With these measurements, the student estimates the total distance travelled. How should the student report the result?

The temperatures of two bodies measured by a thermometer are $t_{1}=20^{\circ} C \pm 0.5^{\circ} C$ and $t_{2}=50^{\circ} C \pm 0.5^{\circ} C$ Calculate the temperature difference and the error theirin.

A student performs an experiment to determine the Young's modulus of a wire, exactly $2 \mathrm{~m}$ long, by Searle's method. In a particular reading, the student measures the extension in the length of the wire to be $0.8 \mathrm{~mm}$ with an uncertainty of $\pm 0.05 \mathrm{~mm}$ at a load of exactly $1.0 \mathrm{~kg}$. The student also measures the diameter of the wire to be $0.4 \mathrm{~mm}$ with an uncertainty of $\pm 0.01 \mathrm{~mm}$. Take $g=9.8 \mathrm{~m} / \mathrm{s}^2$ (exact). The Young's modulus obtained from the reading is

We can reduce random errors by

If a copper wire is stretched to make its radius decrease by $0.1\%$ , then percentage increase in resistance is approximately ………. $\%$