Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Multiple-Choice Questions (Junior Science Level) Energy Use at Home Home Heating

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 1 You come into a cold room and switch on the space heater. Which statement is true during the time when the temperature in the room is rising? A.The power delivered by the heater is larger than the heat lost from the room. B.The power delivered by the heater is smaller than the heat lost from the room. C.The power delivered by the heater is the same as the heat lost from the room. Home Heating

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 1 Answer You come into a cold room and switch on the space heater. Which statement is true during the time when the temperature in the room is rising? A.The power delivered by the heater is larger than the heat lost from the room. B.The power delivered by the heater is smaller than the heat lost from the room. C.The power delivered by the heater is the same as the heat lost from the room. Home Heating

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 2 On a cold, still day, you are trying to determine the energy balance of your home. Which of these assumptions of energy flow is unreasonable? Home Heating House Heat generated inside house C (heat loss to cold air through conduction) A Energy Flow In (from sunshine) B Energy Flow In (“fuel”) D (heat loss to the air through convection) E (heat loss to cold air through radiation)

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 2 Answer On a cold, still day, you are trying to determine the energy balance of your home. Which of these assumptions of energy flow is unreasonable? Home Heating House Heat generated inside house C (heat loss to cold air through conduction) A Energy Flow In (from sunshine) B Energy Flow In (“fuel”) D (heat loss to the air through convection) E (heat loss to cold air through radiation)

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 2 Solution Home Heating The sun’s radiation energy will enter the house through the window. The furnace will heat up the house, as will many appliances within the house (lights, people). As the house warms up, heat will be lost to the air through radiation and convection, not conduction. This is because the heat is lost to a mobile fluid (the air), not a solid, even though the mobile fluid is still. If it were a windy day, it would be forced convection.

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 3 Suppose you are an astronaut in space, hard at work in your sealed spacesuit. The only way that you can transfer heat to the environment is by: A.Conduction B.Convection C.Radiation D.Evaporation Home Heating

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 3 Answer Suppose you are an astronaut in space, hard at work in your sealed spacesuit. The only way that you can transfer heat to the environment is by: A.Conduction B.Convection C.Radiation D.Evaporation Home Heating

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 3 Solution In space there is no matter. Both conduction and convection require matter to transfer heat. Radiation as means of heat transfer does not require any medium and there is no exchange of mass. Home Heating

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 4 A.Less than $ 25 B.$ 25 C.$ 50 D.$ 100 E.More than $ 100 Home Heating A kWh in B.C. costs currently ~ 7.0 cents. The total energy consumption in a 1000 ft 2 (~100m 2 ) large apartment is approximately 200 MJ per day. If the apartment is heated electrically, what’s the energy cost each month?

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 4 Answer A.Less than $ 25 B.$ 25 C.$ 50 D.$ 100 E.More than $ 100 Home Heating A kWh in B.C. costs currently ~ 7.0 cents. The total energy consumption in a 1000 ft 2 (~100m 2 ) large apartment is approximately 200 MJ per day. If the apartment is heated electrically, what’s the energy cost each month?

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Question 4 Solution Home Heating