Volume V.S. Mass
2 short questions
Parents, come try along with your kids.
Questions
1) John hang 2 similar metal balls Q and R on a rod and placed a lit candle under metal ball Q.
What will happen to the rod after heating metal Q for 5 minutes?
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2) The original volume of the water was 10cm³. When a hollow cube was placed in the water, the total volume became 25cm³.
John took out the cube and placed two marbles inside the cube before placing it back into the water.
What will be the new total volume now?
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ANSWERS:
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1) The rod remains at the same position
2) 25cm³
Before my explanations, lets watch this video below
Volume and Mass are completely different things.
Volume = Amount of SPACE an object occupies
Mass = Amount of SUBSTANCE in an object
In question 1, ball Q will gain heat and expanded, but do bear in mind that when the ball gain heat and expand, the amount of substance in the metal ball is the same. The amount of molecules in the ball is the same, just that they became a little bigger.
In question 2, the marbles are placed INSIDE the cube. The space occupied by the cube in the water did not change. The amount of space the cube occupy is the same.
How to differentiate if the question is testing you on volume or mass?
Diagrams testing on volume
Diagrams testing on mass
You will see beam balance
I would normally get my kids to write down "Volume" or "Mass" at the side of the diagram of questions so that they do not forget and stay on track.
Volume = SPACE OCCUPIED
E.g. The space occupied by the air is the same hence the volume remains the same.
E.g. Object A occupy more space than object B, hence it has a larger volume.
Mass = SUBSTANCE IN OBJECT
Substance can be in the form of Solid, Liquid and Gas.
E.g. As John pump in more air, the balloon became heavier and the beam balance will tilt towards the balloon. (Substance is air in this case)
E.g. As John placed more marbles in the container, it became heavier.
E.g. As Mary poured out some water from the container, the mass decreased.
