Surface Area Of Cube, Cuboid And Cylinder
Chapter Name : Mensuration |
Sub Topic Code : 104_08_11_06_03 |
Topic Name : Surface Area Of Cube, Cuboid And Cylinder |
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Sub Topic Name : Cylinder |
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Introduction
With the help of a graph sheet & a cylindrical tin, you are taught how you can build a cylinder model & arrive at the surface area formulas
Pre-Requisites:
About different solids- namely Cube, cuboid & Cylinder and their importance
Activity:
Take few shuttles (badminton). Depending on the area of each shuttle & the number of shuttles, decide what should be the length of the box and the area of the top & bottom cover as well. From that, arrive at the lateral & total surface areas
Real Life Question:
How much area of the cylinder must be coated with wax such that the pouring materials do not stick to the container?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Lateral Surface Area | 2?rh |
| Total Surface Area | 2?r(r + h) |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| Waste plastic container (cylindrical shape) in your house | First pierce the top & bottom and remove the circular covers. Observe around the curved surface; there will be a slit line. With the help of a large scissors, cut it along the slit & open it. Notice that it is in rectangular shape. Now, with the help of these, try to draw the net of a cylinder |
Real life uses :
Large overhead tanks are sometimes cylindrical, especially when the availability of space is very less. The pipelines laid underground, from where you get your drinking water are also cylindrical in shape
Places to visit :
Construction site, Temples, Super Markets
Practical examples around us
| Examples | Explainations |
|---|---|
| Construction site, Temples, Super Markets | The pencil (unsharpened) is also in the shape of a cylinder |
| Cold Drink Can | Many cold drink tins are most likely to be cylindrical in shape |
What you learn in Theory:
The curved surface of the cylinder, is actually a rectangle with an area = 2?rh, where r is the radius of the base & h is the height of the cylinder
What you learn in Practice:
Cylindrical shape is very common around us. In constructions, they are used for better feasibility, aesthetics & economical purposes. Elsewhere, convenience may also be one of the reasons (because cuboids & cubes have sharp corners)