GED Science Physical Science 3 — Questions and Answers
Question 1: A skateboarder at the top of a ramp has potential energy of 500 J. At the bottom of the ramp, assuming no friction, what is the skateboarder's kinetic energy?
- 250 J
- 500 J (Correct answer)
- 1000 J
- 0 J
Correct answer: 500 J
By conservation of energy, all potential energy converts to kinetic energy when there is no friction.
Question 2: Which of the following best describes a conductor?
- A material that does not allow electric current to flow
- A material that stores electrical charge
- A material that allows electric current to flow easily (Correct answer)
- A material that converts electricity to heat only
Correct answer: A material that allows electric current to flow easily
Conductors have loosely held electrons that allow electric current to pass through them easily.
Question 3: Two objects attract each other gravitationally. If the distance between them is doubled, the gravitational force between them becomes:
- Four times greater
- Two times greater
- One-half as great
- One-fourth as great (Correct answer)
Correct answer: One-fourth as great
Newton's law of gravitation states force is inversely proportional to the square of the distance, so doubling distance reduces force to 1/4.
Question 4: Which phase change occurs when a liquid becomes a gas?
- Condensation
- Freezing
- Sublimation
- Evaporation (Correct answer)
Correct answer: Evaporation
Evaporation (or vaporization) is the phase change from liquid to gas.
Question 5: A substance has a pH of 2. This substance is best described as:
- Strongly basic
- Neutral
- Weakly acidic
- Strongly acidic (Correct answer)
Correct answer: Strongly acidic
A pH of 2 is well below 7, placing it in the strongly acidic range of the pH scale.
Question 6: Which of the following is an example of a chemical change?
- Ice melting into water
- Sugar dissolving in water
- Iron rusting (Correct answer)
- Glass breaking
Correct answer: Iron rusting
Rusting is a chemical change because iron reacts with oxygen and water to form a new substance, iron oxide.
Question 7: Sound travels fastest through which medium?
- Vacuum
- Air
- Water
- Steel (Correct answer)
Correct answer: Steel
Sound travels fastest through solids like steel because particles are more closely packed, allowing faster transmission of vibrations.
GED Science Physical Science 3
A skateboarder at the top of a ramp has potential energy of 500 J.
At the bottom of the ramp, assuming no friction, what is the skateboarder's kinetic energy?