Question 9
(a) (i) What is a thermometric substance?(ii) Name two thermometric liquids.
(iii) State the reason why the bulb of a thermometer:
(α) has a thin wall;
(β) is small
(b) A quantity of ice at -5oC is gradually heated in a container until it boils at 100oC. With the aid of a sketched graph, explain the variation of its density, ρ, with temperature, T, from -5oC to 100oC.
(c) (i) Define work.
(ii) A vehicle of mass 1.10 x 103 kg moves along a horizontal road at a speed of 12.5 ms-1. Calculate the work required to increase the speed of the vehicle to 25 ms-1.
Observation
Part (a) Performance was low.
Part (b) Performance was below.
Part (c) Performance was poor.
The expected answer is :
A material that has a property that varies uniformly with temperature (ii) Names of thermometric liquids
- alcohol
- mercury (iii) (α)The bulb of a thermometer has a thin wall
to allow for rapid conduction of heat, through the glass, to the liquid
(β)The bulb of a thermometer is small
enable it to respond quickly to change(s) in temperature.
(b)Explanation of the variation of density with temperature of water
- from -5 °C to 0 °C, density decreases due to expansion
- from 0 °C to 4 °C, density increases due to contraction
- from 4 °C to 100 °C, density decreases due to expansion
(c) (i)Definition of work
The product of force and the distance moved in the direction of the force (ii)Calculation of work required to increase the speed of a vehicle from 12.5 ms-1 to 25 m s-1
