How Much Would a Person Weigh on Mars Compared to Earth?

When discussing the weight of a person on different planets, it's important to distinguish between mass and weight. While mass is a measure of the amount of matter in an object and does not change with location, weight is a force due to gravity and varies depending on the gravitational pull of the planet. This article will explore how the weight of a 90 kg person on Earth compares to their weight on Mars.

90 kg on Earth vs. Mars

Mass is a fundamental property and does not change when an object is moved from one planet to another. Therefore, a person weighing 90 kg on Earth would still weigh 90 kg on Mars. The key difference lies in the weight, which is the force exerted on that mass due to gravity.

To convert mass to weight, we use the gravitational acceleration (g):

On Earth: 90 kg x 9.81 m/s2 882 N or approximately 198 lbs. On Mars: 90 kg x 3.71 m/s2 334 N or approximately 75 lbs.

Thus, the weight of a 90 kg person on Mars is about 43% of their weight on Earth, illustrating the significant difference in gravitational force between the two planets.

What About 100 kg on Earth?

For a person who weighs 100 kg on Earth, the gravitational force experienced is calculated as follows:

On Earth: 100 kg x 9.81 m/s2 981 N or approximately 218 lbs. On Mars: 100 kg x 3.71 m/s2 371 N or approximately 82 lbs.

A 100 kg person on Mars would weigh about 38% of what they weigh on Earth, making them feel significantly lighter but without any change in their mass.

Perceived Weight vs. Actual Mass

Perceived weight is the measure of the gravitational force exerted on an object by a planet's surface. Actual mass, on the other hand, is the amount of matter in an object and remains constant irrespective of location.

For example:

Mass: 100 kg on Earth 100 kg on Mars. Weight: 100 kg on Earth 981 N or 218 lbs. (38.5% of Earth's gravity)
100 kg on Mars 371 N or 82 lbs. (37.7% of Earth's gravity)

Therefore, while mass remains constant, weight changes with the gravitational force of the planet.

Common Misconceptions

Many people mistakenly believe that an object's weight can be changed without altering its mass. However, as discussed, weight is a function of the gravitational force acting on an object. Here are a few common misconceptions:

Misconception 1: Height Affects Weight

Height does not affect weight. Weight is determined solely by the mass of the object and the gravitational force exerted by the planet. Therefore, a person's weight remains the same regardless of their height, as long as their mass does not change.

Misconception 2: Mass Equals Weight

Mass is a measure of the amount of matter in an object, while weight is the force exerted on that mass due to gravity. Mass and weight are related but distinct concepts. Mass does not change with location, whereas weight changes.

Conclusion

In conclusion, a person's mass remains constant regardless of their location in the universe. The weight, on the other hand, is dependent on the gravitational force of the planet. A 90 kg person on Earth would weigh about 90 kg on Mars, but their weight would be significantly less due to Mars' lower gravitational pull. Similarly, a 100 kg person on Earth would weigh about 82 lbs on Mars. Understanding the difference between mass and weight is crucial for appreciating the true nature of gravity and its effects on objects.

Frequently Asked Questions (FAQs)

Q: Does my weight change when I go to the moon?

Yes, your weight would change on the moon due to its lower gravity. The moon's gravity is about 1/6th that of Earth, so you would weigh about 1/6th of your weight on Earth.

Q: Does the gravitational force vary within a planet?

While the gravitational force varies slightly with depth within a planet, for most practical purposes, the surface gravity is considered constant. Therefore, the weight of a person on the surface of a planet is assumed to be uniform across that surface.

Q: Can I lose weight by going to another planet?

No, you cannot lose weight simply by going to another planet. Your mass remains the same, but your weight would decrease due to lower gravitational force. However, your weight would increase again on Earth if you were to return.