2.3.4. Consequences of thermal energy transfer
A subsection of Physics, 5054, through 2. Thermal physics
Listing 10 of 23 questions
When a house is heated, energy is lost to the outside. shows where the energy is lost from the house. Calculate the percentage of the energy lost through the roof. Energy is lost through the roof by conduction and from the roof by convection and by radiation. Explain in detail how this happens. Fitting carpets on the floor reduces energy loss. Explain how a carpet reduces energy loss. The table gives information about three methods of reducing energy loss. Calculate the values of X and Y. Which one of these three methods should the house owner choose? Explain your answer. State two other ways, not already mentioned, of reducing energy loss from the house. roof windows 10% walls 35% escape of hot air 15% floors 15% A B C method of reducing energy loss fitting carpets on the floor insulating the roof fitting modern windows installation cost saving on energy costs in one year $600 $10 $300 Y X $20 number of years of saving needed to cover installation costs
5054_s05_qp_2
THEORY
2005
Paper 2, Variant 0
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a shows a room heater. b is a diagram of the electric circuit of the heater. switch A live neutral switch B a b The fuse has not been drawn on the circuit diagram in b. On b, draw the symbol for a fuse in the correct position. State the part of the room heater to which the earth wire is connected. The earth wire reduces the chance of an electric shock if a fault develops in the room heater. 1. State one fault that causes an electric shock when a person uses the room heater without an earth connection. 2. Explain how using an earth connection prevents an electric shock. This type of room heater is very efficient. Explain what this means. The room heater is a convector heater. Describe and explain how thermal energy passes around a room by convection. shows the power output of the room heater when each switch is closed. power / W switch A only closed switch B only closed both switches closed Determine the power output of the room heater when only switch B is closed. power output = The room heater is used with both switches closed for 2.5 hours. Calculate the energy output of the room heater 1. in kilowatt-hours, energy = kW h 2. in joules. energy = J
5054_s12_qp_21
THEORY
2012
Paper 2, Variant 1
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shows the plan of a bedroom and part of the main room of a house. Other rooms are not shown. bedroom 18 °C main room 22 °C outside of house 32 °C door window The temperatures of the main room, the bedroom and the outside of the house are shown on . shows all the thermal energy inputs to the bedroom in one hour. thermal energy input to bedroom through door and walls from main room 50 000 J through walls from outside of house 2 000 000 J through window 1 000 000 J from person sleeping in bedroom 250 000 J Suggest why more thermal energy enters the bedroom from the outside of the house than from the main room. An air conditioner keeps the temperature constant in the bedroom by removing thermal energy. Calculate the total thermal energy that the air conditioner removes from the bedroom in one hour. thermal energy = The electrical power input to the air conditioner is 300 W. Calculate the electrical energy input into the air conditioner in 1 hour. energy = The air conditioner cools the air at the top of the room. This causes a convection current in the room. Explain how the cold air gives rise to the convection current.
5054_s12_qp_22
THEORY
2012
Paper 2, Variant 2
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A house is to be thermally insulated to reduce thermal energy loss and reduce fuel costs. loft insulation: installation cost, $300 energy cost saving, $300 per year cavity wall insulation: installation cost, $700 energy cost saving, $200 per year draught proofing: installation cost, $100 energy cost saving, $30 per year double glazing: installation cost, $7000 energy cost saving, $400 per year Which type of thermal insulation pays back the cost of installation in the shortest time?
5054_s23_qp_11
MCQ
2023
Paper 1, Variant 1
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Questions Discovered
23