# Finding Mass of Object without Scale

• SirSpanky0
In summary, the conversation revolves around finding the mass of an aluminum rod without using a scale. The suggestion is made to calculate the mass by accelerating the rod with a constant force and dividing by the force and acceleration. However, the method of calculating the force needed for acceleration is debated, with suggestions including using Coulomb's Law or Hooke's Law.

#### SirSpanky0

I need to find the mass of an aluminum rod without the use of a scale. I have all the dimensions of the rod but I just don't know the right equations etc. Thanks for the help!

This sounds like it might be a homework problem. Perhaps you know the volume of the rod, and its density?

Maybe you're stuck finding the volume of a "rod". A "rod" could have a lot of shapes, though the first one that springs to mind is that of a circular cylinder.

I think that if this is a homework problem you'd do better if you made some effort to solve it yourself, first (the "show your work" rule) - also, there is a special forum for homework problems.

SirSpanky0 said:
I need to find the mass of an aluminum rod without the use of a scale. I have all the dimensions of the rod but I just don't know the right equations etc. Thanks for the help!
You can accelerate it with a constant force and then divide the force exerted and the acceleration and that will give you the mass. Easy to say, hard to do for a lab experiment in school.

Pete

pmb_phy said:
You can accelerate it with a constant force and then divide the force exerted and the acceleration and that will give you the mass. Easy to say, hard to do for a lab experiment in school.

Pete

Yes, but how are you going to calculate the force with which you accelerate? you may still need a scale.

amt said:
Yes, but how are you going to calculate the force with which you accelerate? you may still need a scale.
It depends on the particular way you choose to accelerate it. If you use two charges then you use Coulombs law. If you use a spring then you use the law for springs (the name evades me at the moment).

Pete

pmb_phy said:
[...]If you use a spring then you use the law for springs (the name evades me at the moment).

Would this be Hooke's Law ($F = kx$)? Sorry if I'm wrong, I just like to think I know what's going on once in a while :tongue:

Last edited:

## 1. How can I find the mass of an object without a scale?

One way to find the mass of an object without a scale is to use the principle of displacement. This involves placing the object in a container of water and measuring the change in water level, as the object will displace its own volume of water. From there, the mass can be calculated using the density of water.

## 2. Can a ruler be used to find the mass of an object?

No, a ruler alone cannot be used to find the mass of an object as it only measures length, not mass. However, if the dimensions of the object are known, the volume can be calculated and then used to find the mass using the density formula.

## 3. Is it possible to find the mass of an irregularly shaped object without a scale?

Yes, the principle of displacement can also be used for irregularly shaped objects. By measuring the change in water level, the volume of the object can be determined and then used to find the mass using the density formula.

## 4. How accurate is using the principle of displacement to find mass?

The accuracy of using the principle of displacement to find mass depends on the accuracy of the measurements taken. As long as the water level is measured accurately and the density of water is known, the mass can be calculated with a high level of accuracy.

## 5. Are there any other methods for finding the mass of an object without a scale?

Another method for finding the mass of an object without a scale is by using the principle of conservation of energy. This involves measuring the object's acceleration due to gravity and using the formula F=ma to calculate the force of gravity on the object. From there, the mass can be calculated using the formula F=mg.