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Description
Flashcards by Sara. H S., updated more than 1 year ago
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Created by Sara. H S.
almost 6 years ago
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| Question | Answer |
| What is the difference between useful energy and wasted energy? | Useful energy is energy that you need while wasted energy is energy that you don't need. |
| What is both the useful and wasted energy from a light globe? | Useful energy: Light Wasted energy: Heat |
| What is the wasted energy released by this example of an energy conversion? Playing Cricket => Initial: Chemical Energy => Useful: Kinetic Energy => ____ Energy | Heat |
| What is energy efficiency? | A measure of how much input energy is converted into output energy. |
| What makes a device energy efficient or inefficient? | If an object has more useful output energy than initial input energy than it is deemed efficient. However, if a device has more until input energy than useful output energy than it is deemed inefficient. |
| What is an example of an energy inefficient device? | An electric fan (or any other plausible answer that shows a device that wastes a lot of its input energy) |
| What is the difference in energy efficiency between a car and a bicycle? | Cars are energy inefficient as only 25% of intial input energy is converted into output useful energy is released while bicycles are energy efficient as 95% of intial input energy is converted into useful output energy. |
| True or False: The human body is more energy efficient than an electric motor. | False |
| What is the formula for energy efficiency? | Energy Efficiency = Useful Energy/Total Output Energy * 100 |
| A battery-operated remotes controlled car uses 1800J of chemical energy. It wastes 1350J of sound and heat energy. What is the percentage of the car's intial input energy that was wasted? | 1800-1350= 450, 450/1800= 0.25, 0.25*100=25%, 100%-25%= [75%] |
| 25% of a lawnmower's initial input energy (3200kJ) was converted into (useful) kinetic energy. What was the amount of useful output energy? | 25%=1/4, 3200/4= [800kJ] |
| What is a way to tell if a device is energy efficient? | Look at the energy rating label. |
| How many stars must a device have in order to be labelled as "super-efficient"? | 6 stars |
| What is insulation? | The protection of something by using interposing material that prevents the loss of heat or the intrusion of sound. |
| What is the National House Energy Rating Scheme? | The Nationwide House Energy Rating Scheme (NatHERS) is a star rating system (out of ten) that rates the energy efficiency of a home, based on its design. |
| What are three achievable improvements that can be done to house design? | •the orientation of windows (e. g. large windows in the northern and eastern side of the house and small to no windows in the western and southern side of the house •tinting or shading west-facing windows •insulating the floor, walls and roof to reduce energy losses. |
| What is one kilowatt hour, (kWh) equal to in both joules (J) and megajoules (MJ)? | 1kWh = 3,600,000J or 3.6MJ |
| What is the regenerative breaking system? | In a battery-powered electric vehicle, regenerative braking (also called regen) is the conversion of the vehicle’s kinetic energy into chemical energy stored in the battery, where it can be used later to drive the vehicle. It is braking because it also serves to slow the vehicle. It is regenerative because the energy is recaptured in the battery where it can be used again. |
| What are the materials that are used to make cars lighter? | Carbon fibre, plastics and aluminum. |
| What does LEDs stand for? | Light-Emitting Diodes |
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