Step 8 of 18 · Forces · SC4-FOR-01
Mass, weight and friction
Mass is stuff, in kilograms. Weight is gravity's pull on it, in newtons.
Learn it
Distinguish mass from weight, calculate weight with W = m × g, and describe the effects of friction
Idea 1 of 4
Mass is the amount of matter
Mass is how much stuff something is made of, measured in kilograms. It is the same wherever you go — on Earth, on the Moon, floating in space.
Know it by heart
Say each one in your head, then tap to check.
Try it
Play — nothing here is marked
W = m × g = 45 × 9.8 = 441 N
- The Moon72 N
- Mercury167 N
- Mars167 N
- Venus401 N
- Earth441 N
- Jupiter1116 N
Your mass is 45 kg on every one of these worlds — you are made of the same amount of stuff. Only your weight changes, because the pull of gravity does.
A full-marks answer
Calculate the weight on Earth of a 45 kg student. (g = 9.8 N/kg)
2 marksBuilt one line at a time — say the next line before you reveal it
- W = m × g(write the formula first — it's worth a mark)
Words to know
Tap a card to flip it
Step 8 · last bit
Ready? Prove it.
A round of ten. Score 8 or more and this step is done — then on to magnets.