Topic 3 Conservation of Energy Flashcards
What is the unit for measuring energy?
joule
What is the name for energy stored in a hot object?
thermal/internal
How is energy transferred from hot objects to their surroundings?
by heating/convection/conduction/radiation/evaporation
Energy stored in petrol in a car is transferred to energy stored in the moving car. What are the names for these two energy stores?
chemical, kinetic
If 100J of energy is transferred into a machine, how much is transferred out?
100J
In what way is most wasted energy transferred?
by heating
When an object is moved to a higher position, what name is given to the energy that it then stores?
gravitational potential energy
What are the energy transfers when a ball bounces?
kinetic, strain/elastic potential, kinetic
What are the energy transfers when a moving car slows down?
kinetic ? thermal energy stored in the brakes/surroundings, energy transferred by forces
Name three different types of object or substance that store energy in chemicals.
food, fuel, batteries/cells
Name two ways in which a television transfers useful energy to its surroundings.
light, sound
Name one way in which a television transfers wasted energy to its surroundings.
by heating
In what way do most machines or processes transfer wasted energy to the surroundings?
by heating
Name two machines in which energy transferred by heating is useful energy.
any two sensible answers, such as cooker or fire
When a kettle boils water, the useful energy ends up stored as thermal energy in the hot water. Where does the wasted energy end up?
thermal energy in kettle/surroundings
When a moving car brakes and comes to a stop, where does all the kinetic energy it was storing eventually end up?
thermal energy in the surroundings
When a moving car hits a wall, what happens to the kinetic energy it was originally storing?
kinetic energy of crash fragments, transferred to surroundings by sound but all ends up as thermal energy in the surroundings
What does dissipated mean?
spread out
Which wastes more energy: a more efficient machine or a less efficient machine?
less efficient
What happens to the particles in a solid when the solid gets warmer?
vibrate more
One end of a metal bar is heated. What is the name for the way energy is transferred along the bar?
conduction
What kind of materials are good thermal conductors?
metals