Energy Sources & Types
What form of energy is stored in a compressed spring?
elastic potential energy
When energy moves from one object to another but the total amount stays the same, we call this what?
conservation of energy
Which thermal transfer involves direct contact between objects?
conduction
Which energy transfer (sound or thermal) is responsible when a bell makes a noise?
sound energy
In a battery-powered toy car, name one energy transfer that happens when it runs
chemical potential energy in the battery → electrical → kinetic and thermal
Name two types of potential energy
gravitational, chemical, and potential
If a pendulum slows down because of friction, where did some of its mechanical energy go?
into thermal energy
Which thermal transfer moves heat by fluid motion (in liquids or gases)?
convection
How can sound energy cause a change in a system (give a simple example)?
a speaker's vibrations can make nearby lightweight objects move or vibrate
For a closed thermos bottle, which energy transfer is reduced the most by the insulated walls: conduction, convection, or radiation?
onduction and convection most reduced; vacuum reduces conduction and convection
Identify the kind of energy an apple has when it hangs on a tree before falling
gravitational potential energy
A falling object converts gravitational potential energygravitational potential energy into what main form of energy?
kinetic energy
Which thermal transfer can move energy through empty space?
radiation
Describe how thermal energy transferred into a metal rod can change that rod.
it can expand or become hotter, changing its shape or temperature
A pot of soup cools faster when uncovered than when covered. Which thermal transfer is increased by leaving it uncovered and why?
radiation and convection — warm vapor and convective currents escape; radiation also lost more freely
A battery provides what type of potential energy that can power a flashlight?
chemical potential energy
Explain why a bouncing ball never returns to its original height (in real life).
some mechanical energy is converted into thermal and sound energy, so total mechanical energy decreases though total energy conserved)
Give one example of conduction, one of convection, and one of radiation that a student can observe at home.
conduction — spoon heating in a hot cup; convection — boiling water circulation; radiation — feeling warmth from the sun
Use a model idea to show how sound energy travels from a tuning fork to water surface and causes ripples — what is being transferred?
mechanical vibrations (sound) transfer through air to the water surface, causing movement in the water
Use energy conservation to explain why a roller coaster car moves fastest at the lowest point of the track.
gravitational potential energy is lowest there and has been converted mostly into kinetic energy, making speed highest; total energy conserved minus losses
Describe how kinetic energy and potential energy change for a skateboarder rolling down a hill from the top to the bottom.
potential decreases while kinetic increases; total energy conserved ignoring losses
Given a closed system with a block sliding and coming to rest due to friction, describe how energy is conserved and identify the energy transfers involved
initial kinetic and/or potential energy is transformed into thermal energy of surfaces and surroundings and sometimes sound; total energy remains conserved)
Describe how the three modes of heat transfer could all occur when heating water on a stove in a metal pot.
conduction from burner to pot and pot to water at contact, convection in the water as warm water rises and cool water sinks, and radiation from burner or hot surfaces to nearby objects
Explain how thermal radiation from a campfire can heat your hands without warming the air between them and the fire much.
radiation transfers infrared energy through space to your hands, increasing their thermal energy even if intervening air stays cooler
Describe all energy forms and transfers during photosynthesis in a leaf as relevant to these standards (focus on energy conservation and types).
radiant energy from sunlight is absorbed and converted into chemical potential energy in sugars; some energy is reflected or lost as heat; energy is conserved across those transfers