SME
Grade 5 Science · Physical Science
Conservation of mass
Use this for “200 g of water, 20 g of salt and a 30 g cup. What does the scale read after stirring?”
Diagram
200 g + 20 g + 30 g = 250 g
This is an example. Type your own values to start a new problem.
Water (g)
+
Salt (g)
+
Cup (g)
=
Total on the scale (g)
Formulas
200 + 20 + 30 = 250
Water + salt + cup = total on the scale
Assumptions
•
Weigh the cup, the water and the salt together, then stir until the salt disappears.
•
The scale reads the same after stirring. Dissolving hides the salt but does not remove it.
•
Melting, freezing or heating in a closed container also keeps the total mass the same.
Step-by-step
WE KNOW
Water: 200 g
Salt: 20 g
Cup: 30 g
FIND
total on the scale
Step 1 · Find total on the scale
200 + 20 + 30 = ?
Water + salt + cup = total on the scale
Add up all the masses on the scale.
Total on the scale = 250 g
Check
Put the numbers back in. Both sides should match.
200 + 20 + 30 = 250 ✓
Topic check
See what you know: 5 questions on this topic
New questions each time. Pass to mark it complete.