# Measuring mass of something

1. Apr 20, 2013

If a person has actually 1 kg(for example)(on earth)how will a beam balance recognize it?What if the person was on the moon, will the beam balance show 1kg there too?if so How?

And how can one find gravitational acceleration if he does not know mass of an object(he knows Force)

Last edited: Apr 20, 2013
2. Apr 20, 2013

### Staff: Mentor

The mass is independent of the location.
It compares it with a reference object with known mass.
Why should it give a different result?
Let it drop down, and measure the acceleration? There is a better solution, but I get the impression this could be a homework problem.

3. Apr 20, 2013

Its Not a homework problem.
A beam balance on earth measures 1 kg as approximately 10N.
What will happen when the balance is on moon?1kg has now a force of 1.8N
Beam balance recognize 10N as 1kg (I think)
When moon exerts 1.8N on 1kg,Will not the readings differ now?
Will not it show a mass of 0.18Kg

4. Apr 20, 2013

### Staff: Mentor

A beam balance just compares two masses.

5. Apr 20, 2013

Doesn't a beam balance rely on the forces acting on them?

6. Apr 20, 2013

### Staff: Mentor

Here's a picture of a beam balance (an old fashioned one):

Two masses that balance on earth will still balance on the moon.

7. Apr 20, 2013

### Staff: Mentor

All that matters is that the forces are equal.

8. Apr 20, 2013

9. Apr 20, 2013

### Staff: Mentor

Give me an example of just what you mean. It depends on how the "balance" works. If it's really a balance, then it won't matter.

10. Apr 20, 2013

a balance recognize 10N as 1kg
moon exerts 1.8N to 1kg.
will it differ?
Are there other balances that does not depend on forces?

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11. Apr 20, 2013

### Staff: Mentor

The scale you illustrated measures the displacement of a spring, which is proportional to the force exerted. The scale is marked in kg for use on earth. Take it to the moon and you'll get the "wrong" reading. If the scale is marked in Newton's, it will work just fine.

The beam balance that I illustrated will compare two masses. Works just as well on the moon as on earth.

12. Apr 20, 2013