Understanding Mass and Weight

This question asks about the mass of a person on the surface of the Moon compared to their mass on the surface of the Earth. To answer this, we need to understand the difference between mass and weight.

• Mass: Mass is a fundamental property of an object that measures the amount of matter it contains. It is a scalar quantity, meaning it only has magnitude and no direction. Mass is an intrinsic property of an object and does not change with location or the force of gravity.
• Weight: Weight, on the other hand, is the force exerted on an object due to gravity. It is a vector quantity, having both magnitude and direction (towards the center of the gravitational source). Weight depends on both the mass of the object and the strength of the gravitational field it is in. The formula for weight is $W = m \times g$, where $m$ is mass and $g$ is the acceleration due to gravity.

Mass on Earth vs. Mass on Moon

The question states that the person's mass on the surface of the Earth is 60 kg. As we discussed, mass is a measure of the amount of matter in a body. This amount of matter does not change whether the person is on Earth, the Moon, or in space.

Gravity on the surface of the Moon is significantly weaker than gravity on the surface of the Earth (approximately one-sixth). This difference in gravity affects the person's weight, but not their mass.

Since mass is an intrinsic property and remains constant regardless of the gravitational pull, the mass of the person will be the same on the surface of the Moon as it is on the surface of the Earth.

Given the mass on Earth is 60 kg, the mass on the Moon will also be 60 kg.

Conclusion

The mass of a person is a measure of the amount of matter in their body, which does not change with location. While the gravitational force (and thus weight) varies depending on the celestial body, the mass remains constant.

Therefore, if the mass of a person is 60 kg on the surface of Earth, their mass on the surface of the Moon will also be 60 kg.

Revision Table: Mass vs. Weight

Additional Information on Gravitational Force

The acceleration due to gravity ($g$) is different on Earth and the Moon. Approximately:

• $g_{\text{Earth}} \approx 9.8 \, \text{m/s}^2$
• $g_{\text{Moon}} \approx 1.62 \, \text{m/s}^2$ (about $1/6$ of Earth's gravity)

This means a person with a mass of 60 kg would have:

• Weight on Earth: $W_{\text{Earth}} = m \times g_{\text{Earth}} = 60 \, \text{kg} \times 9.8 \, \text{m/s}^2 \approx 588 \, \text{N}$
• Weight on Moon: $W_{\text{Moon}} = m \times g_{\text{Moon}} = 60 \, \text{kg} \times 1.62 \, \text{m/s}^2 \approx 97.2 \, \text{N}$

So, the person would weigh much less on the Moon, but their mass (the amount of stuff they are made of) stays the same.