Question 9
-
(a) State two practical applications of good conductors of heat.
(b) Complete the table below.
Types of thermometer
Thermometric property
Bimetallic thermometer
Differential expansion of two different metals
(i)
Change in volume/length of liquid with temperature
(ii)
Resistance thermometer
(iii)
Gas thermometer
(c) Give two examples to show that water expands when freezing.
- The cross-sectional area of the two pistons of hydraulic press are 0.2 m2. If an effort of 20 N is applied to the smaller piston, calculate the force on the larger piston.
- An electric water heater raises the temperature of 10 kg of water from 15oC to 85oC.
If the efficiency of the heater is 90%, calculate the energy it consumes in
- joules
- kWh
Observation
The expected answer is:
9. (a) Good Conductors of Heat
e.g for making
- cooking utensils (Aluminium cooking pots)
- hot-plate (stove)
- heat exchangers/car radiator (boilers in nuclear reactors)
- circuit breaker
(b) (i) Liquid-in-glass
(ii) Electrical resistance
(iii) Pressure at constant volume/Volume at constant pressure
(c) Two Examples
- Cracking of a corked glass bottle filled with water when freezing takes place
Floating of ice (block) on water surface
