A group of students carried out an investigation into the rate at which different foods cool down. They measured the temperature of each food at 30 second intervals until the food had cooled from 80 C to room temperature. They then drew graphs of the results. In each case, the graph was the same shape. Which of the following describes the shape of their graphs?
15%
A linear graph with a negative gradient
8%
A lineear graph with a positive gradient
62%
A curved line graph with a negative gradient that is steeper at higher temperatures
15%
A curved line graph with a positive gradient that was steeper at lower temperatures
Q.2.
A cool box is used to keep food cooler than the surroundings. They are often used to carry chilled or frozen food home from a supermarket or to keep food fresh at a picnic. Which of the following materials would be suitable to make the walls of a cool box?
33%
Aluminum alloy
22%
Thin plastic
11%
Thick plastic
33%
Polyurethane foam (a type of plastic that contains air bubbles)
Q.3.
Which way does thermal energy travel?
50%
From hotter to cooler
14%
From cooler to hotter
29%
From a conductor of heat to a non conductor
7%
It varies depending on the situation
Q.4.
If 18,000 J of energy was transferred from an electric heater over the course of 2 minutes, what is the rate that heat was transferred?
42%
150 J/s
17%
150 W/s
33%
9,000 J/s
8%
9,000 W/s
Q.5.
LEDs are low energy alternatives to conventional light bulbs but they still generate a lot of heat when they are switched on. They need to be attached to a heat sink to keep them cool. Which of the following would make a good heat sink for an LED?
12%
A solid block of plastic
25%
A solid block of metal
25%
A block of polystyrene foam
38%
A metal plate with fins
Q.6.
Which of the following features of a thermos bottle is designed to reduce the rate of heat transfer by radiation?
38%
The vacuum
12%
Cork base
12%
The lid
38%
Silvering the side walls
Q.7.
The smallest fox in the world, the fennec fox, lives in the Sahara desert. It has very large ears. How do its ears help it to keep cool?
22%
They can be flapped backwards and forwards creating a cool breeze over the fox
22%
The fox can twist and bend its ears to shade itself from the Sun
56%
They have a large surface area
0%
They don't help at all
Q.8.
18,000 J of energy was transferred from an electric heater to a 2kg block of steel. The temperature increased by 18 C. Based on these figures, what is the specific heat capacity of the steel?
25%
500 J/kg
25%
3,600 J/kgoC
50%
500 J/kgoC
0%
3,600 W/kg
Q.9.
Which of the features of a thermos bottle is designed to slow down the rate of heat transfer by reducing both conduction and convection?
43%
The vacuum
29%
Cork base
14%
The lid
14%
Silvering the side walls
Q.10.
Which of the following would be the conductor of heat?
62%
Copper
38%
Wood
0%
Aluminium
0%
Brass
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