Properties Of Matter And Their Measurement
Chapter Name : Some Basic Concepts Of Chemistry |
Sub Topic Code : 102_11_01_03_02 |
Topic Name : Properties Of Matter And Their Measurement |
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Sub Topic Name : Mass And Weight |
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Introduction
We begin by differentiating between mass and weight and go on to discuss volume, density, temperature as well as the question of reference standards- for universal units for measurement.
Pre-Requisites:
Force, Gravity, Calibration.
Activity:
1. From above, a ping pong ball floats while an iron nail sinks- because the nail has much higher density. 2. While travelling in a lift or a roller coaster, you feel a sense of weightlessness and your stomach plummets. This is because your weight has changed, due to the change in gravity while rushing down, although mass remains static.
Real Life Question:
When we stand on a weighing scale, what are we measuring- weight or mass? Why does an iron rod sink while a ping pong ball floats? How do we know how much 1 kg exactly is?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Mass | The amount of matter in a given substance. |
| Weight | The amount of force exerted by gravity on an object. |
| Volume | The amount of 3 dimensional space occupied by a given object. |
| Density | The amount of mass within a given volume of a given substance. |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| A glass of water, ping pong ball and iron nail. | Put the ball and the nail by turn into the glass of water. The nail sinks while the ball floats, showing that the ball has much lesser density. |
Real life uses :
Suppose you are drowning. Learning about density will make you realize that objects like your shoes and belt will weigh you down and increase chances of drowning, so you’ll take them off and be able swim more easily.
Places to visit :
As mentioned above, experiences in a lift or roller coaster reinforce the concept of mass and weight, while simple home experiments using water, an iron nail and a plastic ball give us a sense of density.
Practical examples around us
| Examples | Explainations |
|---|---|
| Travelling in a lift or a roller coaster. | While going down, you plummet and feel a sense of weightlessness. Here your weight has changed (because the gravity is different while travelling in a lift) but mass remains the same. |
What you learn in Theory:
The difference between mass and weight, and the concepts of volume, temperature and density. Also an explanation of reference standards for universal units of measurement.
What you learn in Practice:
We learn why we weigh much less on the moon but our mass remains the same, why a ping pong ball floats on water but an iron nail doesn’t and why we feel weightless while going down on a roller coaster.