The Volume of a piece of wood $($which floats in water$)$ can be measured as shown. Write a brief paragraph to describe the procedure. State the volume of the wood.

State the measurements shown in the diagrams on the scale of the vernier calipers.

State the measurements shown in the diagrams on the micrometer screw gauge.

A student measures the density of a piece of steel. She uses the method of displacement to find its volume. Her measurements are shown in the diagram. Calculate the volume of the steel and its density.

A pendulum is timed, first for $20$ swings and then for $50$ swings.

time for $20$ swings$=17.4 \mathrm{s}$

time for $50$ swings$=43.2 \mathrm{s}$

Calculate the average time per swings in each case, The answers are slightly different. Suggest some possible experimental reason for this.