SME
Grade 8 Science · Problem type
Your weight on other worlds
Use this for “A 50 kg student weighs 490 N on Earth. What would she weigh on the moon?”
Table
Pull on each kilogram (g)
(N/kg)
Weight (W)
(N)
This is an example. Type your own values to start a new problem.
W (N)
=
m (kg)
×
g (N/kg)
Formulas
W
=
m
×
g
(weight
=
mass
×
pull
on
each
kilogram)
490 = 50 × 9.8
Assumptions
•
Mass is how much matter you are made of: the same everywhere. Weight is gravity’s pull on it, in newtons.
•
On Earth each kilogram is pulled with 9.8 N; on the moon with 1.6 N, so you would weigh about a sixth as much.
•
A bigger planet does not always pull harder at its surface: Saturn is huge but spread out, so its surface pull is close to Earth’s.
Step-by-step
WE KNOW
m = 50 kg (mass), g = 9.8 N/kg (pull on each kilogram)
FIND
weight (W)
Step 1 · Find weight (W)
Use W = m × g (weight = mass × pull on each kilogram)
Each
kilogram
is
pulled
with
g
newtons:
multiply.
W
=
50
×
9.8
W
=
490
N
Check
Put the numbers back in. Both sides should match.
490 = 50 × 9.8 ✓
Topic check
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