S2 Science. Heat. Homework Booklet

Transcription

1 S2 Science Heat Homework Booklet 1

2 1. The graph below shows how most substances cool after being taken away from the source of heat. Answer these questions about the graph a. where is the heat loss the greatest: A, B, C or D? b. What is the temperature at point C? c. What is the room temperature? d. What is happening at points A, B, C, and D? e. Draw a simple cooling graph like this graph. Add two more cooling lines with the following characteristics: i. same starting temperature, higher room temperature ii. higher starting temperature, lower room temperature. 2

3 3. These two beakers were both filled with water at 80 o C and left to cool down in a room at 20 o C. a. What temperature will both beakers eventually end up at? b. What beaker will cool down the fastest? c. Draw a temperature / time graph like the one in question 1 above. You will need two lines one for each beaker. 4. Do houses lose heat faster in the winter or summer? a. Explain your answer. b. Explain how this affects the heating bills. 3

4 5. Describe then explain what you see when two metal rods are heated. 6. In terms of particles explain how the heat travels through solids. 7. Copy and complete the table below to show how metals are used in the home because they are good conductors. 4

5 8. Look at these items used in the house Work out what job each article is used for and write your ideas into a table using these headings: Name Table matt What it is made of Conductor or Insulator What is its job To stop heat from hot plates damaging the table. 5

6 9. Choose the most suitable material from the list below for each of these jobs. Explain your answer. copper polystyrene glass aluminium wood air iron fibre glass a. a beaker to keep a drink warm for longest. b. a base for a saucepan c. a handle for a saucepan d. a material for insulating the roof of a house. 10. Use these pieces of apparatus to draw a diagram showing the experiment you did to demonstrate convection currents. Remember to show the convection current as shown up by the dye. 6

7 11. Why do electric kettles have the heating element placed at the bottom? 12. Copy this diagram of a kettle and add arrows to show the convection currents. 13. Why is the outlet pipe at the top of a water tank? 14. Why is the freezing compartment of a fridge at the top of the fridge? 15. Why is it not vital to have the top of a chest freezer closed all the time? 16. What is the main difference between conduction and convection? 7

8 17. Give another name for heat rays. 18. Copy the diagram and draw the direction of heat movement from the Sun to the Earth. 19. If hot water was poured into each flask which flask cools down the fastest? a. How did the flasks lose the heat energy? b. Where did the energy go? 20. What should be made the same to make this a fair comparison? 21. Describe how these flasks could be used to prove that black is a better absorber of heat rays than shiny surfaces. What extra equipment would you need? 8

9 22. On sunny days drivers put a shield up inside the windscreen explain how the shield helps keep the car cool. 23. In sunny countries food can be cooked in a solar cooker. Draw a diagram to show how the solar cooker works. 24. Explain in terms of heat rays why fire fighters wear silver suits. 9

10 25. Explain how the Thermos flask prevents heat loss by: a. convection b. conduction c. radiation. d. Why is a Thermos flask good at keeping drinks cold as well as hot? 26) Design a container that could be used to carry hot fish and chips from a chip shop to your home without them going cold. Draw a diagram of your design and label any special features. Explain why you have put these features into your design. 10

11 27) Look at this diagram of heat loss from a house a) Ask your teacher for a piece or graph paper and draw a bar graph to show how much heat is lost through each part. b) Describe what you could do to reduce each of the heat losses shown. 28) Explain each of the following statements. a) Houses in hot countries are usually painted white. b) Car radiators are painted matt black. c) Anyone standing near a bonfire feels a draught. d) If you stand in front of an open refrigerator you get cold feet. e) Birds fluff up their feathers in winter. 11

12 28) The diagram bellow shows a house designed to save as much heat energy as possible. The labels indicate features of the house that help in this energy saving. a) Explain how each of the six features shown in the diagram helps save heat energy. b) Some of the energy saving features are more expensive to install than others. The table shows roughly how long it takes before they pay for themselves and start to show a profit. c) Which energy saving feature is the most cost effective? 12

13 d) Which energy saving feature is the least cost effective? e) Solar (sunlight) energy is free. Suggest why it takes so long for a house owner living in Scotland to recover the cost of installing solar panels. f) People living in houses close to airports don t just fit double glazing to reduce heat loss. Give one other advantage of fitting double glazing. 29) Explain each of the following statements. a) A saucepan has a copper bottom but a plastic handle. b) Someone feels cold in a string vest, but warm if they wear a tight shirt over it. c) It is safer picking up a hot dish with a dry cloth than a wet one. d) Hot water tanks have a heater fitted at the bottom rather than the top. e) Seeds germinate (start to grow) earlier in soil that is covered with black plastic sheeting. f) Divers stay warm in cold water by wearing a wetsuit water is trapped between the rubber suit and the diver s skin. g) Paper decorations flutter if they are put on a wall above a hot room heater. h) Glider pilots can gain height by flying over large ploughed fields. 13