When a brick is taken from the earth's surface to the moon, its mass

Analyze the question: The question asks what happens to the mass of a brick when it is moved from Earth to the Moon. The key is knowing the difference between mass and weight.

Explain the concept:

• Mass is the amount of matter in an object. It is measured in kilograms (kg) and does not depend on location.
• Weight is the force of gravity acting on the mass: W = mg. It is measured in newtons (N) and changes with the gravitational field strength, g.

Solution:

1. On Earth, g ≈ 10 m/s² (or 9.8 m/s²). On the Moon, g ≈ 1.6 m/s², about one-sixth of Earth's.
2. Take a brick of mass 2 kg. • Weight on Earth = 2 × 10 = 20 N • Weight on the Moon = 2 × 1.6 = 3.2 N
3. The weight reduces, but the brick is still made of the same amount of matter, so its mass is still 2 kg.
4. Mass would only change if matter were added to or removed from the brick. Travelling to the Moon does neither.

Checking the options:

• A. Remains constant: correct, because mass is independent of location.
• B. Reduces: this describes the weight, not the mass.
• C. Increases: nothing adds matter to the brick.
• D. Becomes zero: only weightlessness in free space would give zero weight, and even then the mass is not zero.

Exam tip: Remember "Mass is Matter, Weight is Where." Mass stays the same everywhere, while weight depends on where you are (the gravitational field). JAMB often tests this distinction, so whenever a question moves an object to another planet, the Moon, or a mountain top, ask yourself whether it is asking about mass or weight.