The density of iron is 7.8 g/cm³. Write it in kg/m³…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
The density of iron is .
- Write it in .
- What is the volume of a iron dumbbell, in cubic centimetres?
Need a reminder? The key ideaShow
To change a unit, multiply by a fraction that equals one, such as , so that the old unit cancels. A prefix goes with the unit's power:
Density is mass over volume, .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. Density. .
Step 2. Volume. .
Answer: (a) . (b) About .
Check. is a cube about on a side: a small, heavy dumbbell. Sensible.
Watch out. Keep the units matched: grams with , or kilograms with . Mixing them is off by a factor of .
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