Forms of Energy
What type of energy does a moving bicycle have?
Mechanical energy (specifically kinetic energy)
A light bulb changes electrical energy into light energy. Is this a transfer or a transformation?
Transformation — electrical energy changes into light energy.
What is the ability to cause change or do work called?
Energy
You feel warmth from a campfire without touching it. What type of heat transfer carries energy directly from the fire to you?
Radiation
A student plugs in a toaster. What type of energy is transformed into thermal energy?
Electrical energy
A glowing light bulb produces light and becomes hot. Name the two forms of energy it produces.
Radiant (electromagnetic) energy and thermal energy
A bowling ball rolls into stationary pins, causing them to move. What happens to energy?
Energy is transferred from the moving ball to the pins.
What is the law stating that energy cannot be created or destroyed, only transferred or transformed?
Law of conservation of energy
A wooden spoon and a metal spoon sit in equally hot soup. Why might the metal spoon's handle become warm more quickly?
Metal conducts thermal energy more effectively than wood.
An ice cube melts when placed in a warm room. In which direction does thermal energy transfer?
From the warmer surroundings to the colder ice.
A roller coaster reaches the top of a hill and pauses before descending. Which type of energy is greatest due to its height?
Gravitational potential energy
Sunlight reaches a solar panel, and the panel produces electricity. Identify the transfer and the transformation.
Transfer: radiant energy travels from the Sun to the panel. Transformation: radiant energy changes into electrical energy.
What term describes a circular movement of fluid caused by differences in temperature and density?
Convection current
When a liquid is heated, why can convection currents form?
The warmer liquid expands and becomes less dense, so it rises. Cooler, denser liquid sinks, creating circulation.
A student stretches a rubber band and releases it to launch a paper ball. Describe the energy transformation.
Elastic potential energy transforms into kinetic energy as the rubber band launches the ball. Some energy also becomes sound and thermal energy.
What is the difference between sound energy and radiant energy in how they travel?
Sound requires a medium to travel through; electromagnetic radiation can travel through a vacuum.
A student says, 'Whenever energy moves, it must change into a different form.' Explain why this statement is incorrect.
Energy can be transferred without changing form. For example, thermal energy transfers from hot soup to a metal spoon while remaining thermal energy.
What is the difference between kinetic energy and potential energy?
Kinetic energy is associated with motion. Potential energy is stored energy associated with position or configuration.
A student claims that conduction, convection, and radiation all transfer thermal energy in exactly the same way. Explain why this is incorrect.
Conduction transfers energy through particle interactions, convection transfers energy through the movement of a fluid, and radiation transfers energy through electromagnetic waves.
A roller coaster moves down a hill and speeds up. What happens to its gravitational potential energy and kinetic energy?
Gravitational potential energy decreases while kinetic energy increases.
Two objects have the same mass. One is moving quickly and the other is moving slowly. Compare their kinetic energies and explain your reasoning.
The faster object has more kinetic energy because kinetic energy increases with speed.
A solar-powered car moves across a track. Explain how energy is transferred and transformed from sunlight to the car's motion.
Radiant energy transfers from the Sun to the solar panel. The panel transforms radiant energy into electrical energy, and the motor transforms electrical energy into mechanical energy that moves the car.
What is the difference between thermal energy and temperature?
Temperature measures average particle kinetic energy. Thermal energy is the total energy associated with the random motion and interactions of particles in a substance.
A student draws a diagram showing the particles in a heated solid moving from one end of the solid to the other, like water in a pipe. Identify the error and describe how the diagram should be corrected
In a solid, particles mainly vibrate around fixed positions rather than flowing along the solid. The diagram should show stronger vibrations near the heated end and energy passing between neighboring particles.
A student wants to keep a drink cold and chooses between a metal cup and a foam cup. Which material is generally better for slowing thermal energy transfer, and why?
Foam, because it is a poor conductor and helps reduce thermal energy transfer into the cold drink.