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 TRANSPORTATION Energy Use in Cars 1: Stop-and-Go Driving

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Energy in Cars 1 Where do you think most of the energy from the fuel burnt by a car goes? 1. Accelerating the car up to its cruising speed 2. Overcoming air resistance 3. Overcoming rolling resistance 4. Heat

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Energy in Cars 1 Where do you think most of the energy from the fuel burnt by a car goes? 1. Accelerating the car up to its cruising speed 2. Overcoming air resistance 3. Overcoming rolling resistance 4. Heat

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Energy in Cars 1 Where do you think most of the energy from the fuel burnt by a car goes? Heat. For a typical gasoline engine, only around 25% of the heat energy from the fuel gets converted into mechanical energy which gets used for the first three items on this list. One way of thinking about an engine is that it transforms the chemical energy from the fuel into mechanical energy and heat, like this:

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Energy in Cars 1 Where do you think most of the energy from the fuel burnt by a car goes? Engine Chemical Energy from fuel (100%) Mechanical Energy to car (25%) Heat Energy to outside air. (75%)

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Energy in Cars 1 Given that stopping a bus costs 0.19 litres of fuel, and cars consume litres/km, how long would your commute need to be to save an amount of gasoline equivalent to stopping the bus once? A km B km C km D. 1.0 km E. 2.5 km

Physics and Astronomy Outreach Program at the University of British Columbia Physics and Astronomy Outreach Program at the University of British Columbia Energy in Cars 1 Given that stopping a bus costs 0.19 litres of fuel, and cars consume litres/km, how long would your commute need to be to save an amount of gasoline equivalent to stopping the bus once? A km B km C km D. 1.0 km E. 2.5 km = 0.19 L ÷ L /km