WEIGHT CALCULATOR

Sounds suspiciously like homework to me!

To solve this, you need 2 things, (1) the density of cast iron and (2) the formula for the volume of a sphere.

That's all you get right now.

Mike

Mike is probably right, it does sound like homework!

However, if you want to learn how to solve the problem we can teach you, which is better than just getting an answer that you have no idea how to arrive at.

So, first consider the problem and try to define it in a way that makes sense.

If you are given a mass of an object you can determine its volume. Iron is pretty dense, foam rubber is not. It makes sense to think that if two objects have the same mass, the denser the object, the less physical volume it takes up.

So density is expressed as mass/volume. That is, the mass divided by the volume. If you look up iron's density you will be half way to solving the problem because it is already expressed in a form that is close to what you need.

Typically, it is expressed as grams per cm^3, which is centimeters cubed! That is a box that is 1 cm per side.

I assume you can convert grams to kilograms, so you need to solve for the volume of iron when its mass is 8.5 kg.

Unfortunately, the volume you get is for a cube! You need a sphere. So you need to either derive the formula for a sphere or look it up. Again, unfortunately, the terms of the equation will not be ordered in a fashion to let you solve for the sphere's diameter, so you will need to use algebra to rearrange the equation to solve for the missing term.

If you still need help, give us a yell and we can help walk you through the process you are stuck with.

Once you've done it, let me know, 'cos there's a bloke in Vange turning out replica cannon that can be used to fire it. I'm his agent. <splutter>

Hint for volume

Circumference of a circle = PI *2R

Area of a circle = PI * R²

Volume of Ball = PI * A * R³

Find A and you have it.