Vocabulary
What is the law of conservation of energy?
Energy cannot be created, lost or destroyed. It is only transferred or transformed.
A toaster is plugged in to toast some bread.
Electrical to Thermal.
What does an insulator do?
Slows the transfer of thermal energy.
What are the three types of thermal energy transfer?
Conduction, Convection and Radiation/Radiant Energy.
On a warm day near the ocean, a breeze moves from the water to the land. Why?
Activity 12 reading explains this is due to the sun heating the land faster than the water. On a warm day this causes air above the land to become warmer and less dense, which makes this air rise and then cooler air over the ocean moves onshore to take its place. This movement of cooler air creates the breeze. This cycle of convection continues.
What is absorption?
The process of energy or matter entering a material but not exiting the material.
A soccer player eats a granola bar to play the game.
Chemical potential energy to kinetic energy.
What does a conductor do?
Supports the transfer of thermal energy.
An iron presses onto the clothing. What type of thermal energy transfer is this? Conduction, Convection or Radiation?
Conduction, the materials of different temperature are in contact with each other and the thermal energy transfers from the iron to the clothing.
What is the energy efficiency of a light bulb that has 40 joules of light energy emitted but has 50 joules of electrical energy supplied?
40/50=0.80
0.80 x 100 = 80% Efficiency
The type of energy that has to do with height and mass.
Gravitational potential energy.
Photosynthesis
Light energy to Chemical potential energy.
Why does the air in an oven not burn your hand but the metal rack does?
The air is a worse conductor (better insulator) than the metal so it transfers thermal energy to your hand much slower so it takes longer to burn you than the metal rack.
What factors affect how much thermal energy can be stored in an object?
Mass, material and amount of energy supplied (starting temp).
The main type of energy responsible for a roller coaster "losing" energy along the ride.
Thermal energy (friction between the wheels & track).
What is potential energy?
Energy that is stored due to its position or its condition.
A match being burned is an example of what energy transformation.
Chemical potential energy to thermal energy.
You have been outside at recess too long and are getting sunburn. What type of thermal energy transfer is this? Conduction, Convection or Radiation?
Radiation from the UV light (electromagnetic spectrum).
Explain what it takes for something to heat up or cool down.
To heat up an object it takes a transfer of thermal energy to it from something/somewhere else.
To cool an object down, thermal energy must be transferred somewhere else.
Because thermal energy always goes HOT to COLD.
The efficiency of a gasoline powered car is about 15%.What does this mean?
The car uses 15% of the energy in gasoline for kinetic energy (Motion). The rest is "lost" energy as thermal & sound energy.
What is convection? Please give an example.
The transfer of thermal energy by the movement of fluids of different temperatures.
The hood of the car is very warm after driving. What type of energy transformation is this?
Kinetic energy (motion of the engine) to Thermal energy (heat).
Why does a steel cup feel colder than a paper plate?
The steel cup conducts thermal energy from your hand much faster than the paper plate.
Explain the difference between thermal energy and temperature.
Thermal energy is the internal energy of a substance due to the movement of the particles. (more particles = more thermal energy)
Temperature is the average kinetic energy of the particles of a substance.
What is the energy efficiency of a light bulb that has 63 joules of light energy emitted but has 72 joules of electrical energy supplied?
63/72=0.875
0.875 x 100 = 87.5% Efficiency