Weight on the moon

What you need:

• some time and patience
• Interest in science

Weight, gravity and mass

To say it in advance: The colloquial language understands the term "weight" (unfortunately) something different than the physicists. Strictly speaking, the term does not appear there, but terms such as "gravity", "weight" and "mass". These should first be explained.

• "Mass" is used in the physics used in a similar way to weight in everyday life. The mass of a body is measured in kilograms, is a measure of how inert a body is and is ultimately determined on a scale in everyday life. It does not matter (at least on earth) whether this is done on a beam balance by comparing it with another weight or on the spring balances that are common for people.
• Gravity, sometimes also called weight, results from the force of gravity: masses pull each other and so are bodies from the earth, from the moon, but also from other planets and of course from the sun dressed. This attraction or gravitational force is of course greater, the greater the two masses are. Two breakfast rolls also attract each other, but the power is extremely tiny.
  instagram viewer

Weight on the moon - the example of "chocolate"

Now it gets a bit tricky, because in solving the problem, masses and forces have to be distinguished!

• A bar of chocolate on the moon naturally has the same mass as on earth - after all, it consists of the same number of atoms and will nourish the astronaut there just as it does here.


What does the earth weigh?

Isn't the earth a good weight? Of course you can't see the globe ...

• However, the moon itself has only about 1/6 the mass of the earth. Accordingly, only 1/6 of the force of gravity that they experience here on earth acts on all bodies there. As a result, the astronauts were able to make considerable jumps there despite their heavy spacesuits.
• Accordingly, a bar of chocolate on the moon is of course only attracted by 1/6 of the earth's weight or gravity, even if its mass has remained the same.
• But what does a scale on the moon indicate? In this case, it doesn't matter which scale you use. With a beam scale, compare a bar of chocolate with a weight of 100 g. These scales will also be balanced on the moon, because the reduction in gravity acts on both bodies (chocolate and weight).
• Both chocolate and a person have "lost weight" on a spring balance, which stretches under the gravity of the body when attached (or placed on). The spring stretches only 1/6 as far as it does on earth, because there is only 1/6 of the force of gravity.
• A good diet? In fact, for a person weighing 70 kg, this spring scale would only show 70: 6 = 11.67 kg. You could... eat a few more bars of chocolate!