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GED Science Energy, Heat, and Waves Summary

Checked 10/26/26

Energy, Heat, and Waves: key points

  • Energy is not created or destroyed; it changes form.
  • Wave speed = frequency × wavelength.
Importance
★★★★★ (5 / 5)
Weight
About 6 of 16 Physical Science questions (35%)

Heat and temperature, conduction, convection, and radiation, endothermic and exothermic reactions, types and sources of energy, and waves and electromagnetic radiation.

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Energy, Heat, and Waves: 10 sample questions

Practice questionReviewedPhysical Science › Energy, Heat, and Waves★★★★★

Question 1. A metal spoon is left in a pot of hot soup, and soon the handle feels hot. How did the heat travel up the spoon?

  1. ① Convection
  2. ② Evaporation
  3. ③ Radiation
  4. ④ Conduction
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Answer: ④ Conduction

Key point: Conduction: heat moves through direct contact

In conduction, heat passes from particle to particle through direct contact. Metals are good conductors, so heat moves quickly from the hot end of the spoon to the handle.

Wrong choices

  • Convection: Convection is heat carried by moving liquid or gas. The spoon is a solid.
  • Evaporation: Evaporation is liquid turning into gas. It does not carry heat up a spoon.
  • Radiation: Radiation is heat carried by waves, like sunlight. The heat here moved through the metal by contact.
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Question 2. A heater warms the air near the floor. The warm air rises, cooler air sinks to take its place, and the air keeps circulating. What is this kind of heat transfer called?

  1. ① Conduction
  2. ② Radiation
  3. ③ Insulation
  4. ④ Convection
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Answer: ④ Convection

Key point: Convection: heat carried by moving fluid (liquid or gas)

Warm air is less dense, so it rises. Cooler, denser air sinks. This circulating movement (a convection current) carries heat around the room.

Wrong choices

  • Conduction: Conduction is heat moving through direct contact, mainly in solids. Here the air itself is moving.
  • Radiation: Radiation travels as waves and does not need moving air.
  • Insulation: Insulation slows heat transfer. It is not a way heat moves.
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Question 3. Energy from the Sun reaches Earth after crossing empty space. How does this energy travel?

  1. ① Convection
  2. ② Radiation
  3. ③ Friction
  4. ④ Conduction
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Answer: ② Radiation

Key point: Radiation can travel through empty space

Radiation is energy carried by electromagnetic waves, such as light and infrared. These waves do not need matter, so they can cross the near-empty space between the Sun and Earth.

Wrong choices

  • Convection: Convection needs a moving liquid or gas. Space is almost empty.
  • Friction: Friction is a force between surfaces. It does not carry energy across space.
  • Conduction: Conduction needs particles touching each other. Space is almost empty.
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Question 4. A hand warmer packet gets hot when it is opened and shaken because a chemical reaction takes place inside. What kind of reaction is this?

  1. ① A nuclear reaction
  2. ② Exothermic, because it releases heat
  3. ③ A reaction with no energy change
  4. ④ Endothermic, because it absorbs heat
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Answer: ② Exothermic, because it releases heat

Key point: Exothermic reactions release heat

An exothermic reaction gives off energy, usually as heat, so its surroundings get warmer. The hand warmer releases heat, so the reaction is exothermic.

Wrong choices

  • A nuclear reaction: Hand warmers use an ordinary chemical reaction, not a nuclear one.
  • A reaction with no energy change: The packet clearly gets warmer, so energy is being released.
  • Endothermic, because it absorbs heat: An endothermic reaction takes in heat and feels cold. The packet gets hot.
Practice questionReviewedPhysical Science › Energy, Heat, and Waves★★★★★

Question 5. An instant cold pack feels cold after the chemicals inside are mixed. What kind of process is this?

  1. ① A process that gives off light
  2. ② Exothermic, because it releases heat
  3. ③ Endothermic, because it absorbs heat
  4. ④ Combustion (burning)
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Answer: ③ Endothermic, because it absorbs heat

Key point: Endothermic processes absorb heat and feel cold

An endothermic process takes in heat from its surroundings. It pulls heat from your hand, so the pack feels cold.

Wrong choices

  • A process that gives off light: The pack does not give off light. It takes in heat.
  • Exothermic, because it releases heat: An exothermic process gives off heat and feels warm. The pack feels cold.
  • Combustion (burning): Burning releases heat and light. The pack gets cold.
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Question 6. Which energy source is renewable?

  1. ① Coal
  2. ② Wind
  3. ③ Oil
  4. ④ Natural gas
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Answer: ② Wind

Key point: Renewable sources are replaced naturally (sun, wind, water)

A renewable energy source is replaced naturally in a short time. Wind keeps blowing because the Sun heats Earth unevenly. Coal, oil, and natural gas are fossil fuels that take millions of years to form.

Wrong choices

  • Coal: Coal is a fossil fuel and is nonrenewable.
  • Oil: Oil is a fossil fuel and is nonrenewable.
  • Natural gas: Natural gas is a fossil fuel. It took millions of years to form and cannot be replaced quickly.
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Question 7. A large rock sits still at the top of a cliff. What kind of energy does the rock have because of its position?

  1. ① Kinetic energy
  2. ② Sound energy
  3. ③ Electrical energy
  4. ④ Gravitational potential energy
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Answer: ④ Gravitational potential energy

Key point: Height gives stored (potential) energy; motion gives kinetic energy

Potential energy is stored energy. A raised object has gravitational potential energy because gravity can pull it down. If the rock falls, that stored energy turns into kinetic energy (energy of motion).

Wrong choices

  • Kinetic energy: Kinetic energy is energy of motion. The rock is not moving.
  • Sound energy: The rock is not making sound.
  • Electrical energy: The rock is not carrying an electric current.
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Question 8. A wave has a frequency of 5 hertz (5 waves per second) and a wavelength of 2 meters. Using speed = frequency × wavelength, what is the speed of the wave?

  1. ① 7 meters per second
  2. ② 2.5 meters per second
  3. ③ 10 meters per second
  4. ④ 0.4 meters per second
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Answer: ③ 10 meters per second

Key point: Wave speed = frequency × wavelength

  1. Speed = frequency × wavelength.
  2. Speed = 5 × 2 = 10 meters per second.

Check: 5 waves pass each second, and each one is 2 m long, so 10 m of wave passes each second.

Wrong choices

  • 7 meters per second: 7 comes from adding 5 and 2. The formula multiplies.
  • 2.5 meters per second: 2.5 comes from dividing 5 by 2. The formula multiplies.
  • 0.4 meters per second: 0.4 comes from dividing 2 by 5. The formula multiplies.
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Question 9. Which type of electromagnetic radiation from the Sun causes sunburn?

  1. ① Ultraviolet (UV) light
  2. ② Microwaves
  3. ③ Infrared radiation
  4. ④ Radio waves
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Answer: ① Ultraviolet (UV) light

Key point: UV light damages skin and causes sunburn

Ultraviolet light has more energy than visible light. It can damage skin cells, which causes sunburn and raises the risk of skin cancer. Sunscreen and clothing block much of it.

Wrong choices

  • Microwaves: Microwaves are not the cause of sunburn.
  • Infrared radiation: Infrared is felt as heat, but it is not the main cause of sunburn.
  • Radio waves: Radio waves have low energy and do not burn skin.
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Question 10. A student filled 4 identical cans with water at 80°C. She wrapped three cans in different materials and left one can unwrapped. After 20 minutes in the same room, she measured the water temperature. Aluminum foil: 52°C Wool: 64°C Cotton: 58°C No wrap: 45°C Why did the student include a can with no wrap?

  1. ① It is a control, so the effect of each wrap can be compared to having no wrap.
  2. ② It makes the water cool faster in the other cans.
  3. ③ It is the independent variable in the experiment.
  4. ④ It measures the temperature of the room.
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Answer: ① It is a control, so the effect of each wrap can be compared to having no wrap.

Key point: A control group shows what happens without the tested factor

A control group is not given the factor being tested. Comparing each wrapped can with the unwrapped can shows how much each wrap slowed the heat loss.

Wrong choices

  • It makes the water cool faster in the other cans.: Each can is separate. The unwrapped can does not change how the others cool.
  • It is the independent variable in the experiment.: The independent variable is the type of wrap. The unwrapped can is the comparison (control) group.
  • It measures the temperature of the room.: The unwrapped can measures how fast water cools without a wrap, not the room temperature.

Test yourself.

Energy, Heat, and Waves: 5 questions →Physical Science: 5 questions →

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