Page 120 - Viva ICSE Science 5 : E-book

More force needed to move the stone Lesser force needed to move the stone

The longer the rod or the lever, the easier it is to move the load. Also, placing the fulcrum
near the load reduces the eff ort needed to move it. Some examples of levers that we use
in our day-to-day life are hammer, tongs, scissors, pliers and nail-clippers.
ACTIVITY TIME

To understand the working of lever

You Need:
5–6 books, a wooden plank, a cylindrical wooden block
What to Do:

• Keep the wooden block in the middle of a table.
• Now place the wooden plank on the block, such
that the block functions as a fulcrum.
• Ask one of your friends to hold the block in place as it might roll while performing the
experiment.
• Now try to lift the pile of books with one hand. Can you lift it easily?
• Next, place the pile of books at one end of the plank as shown in the fi gure.

• Using one hand, press the other end of the plank.
You will observe that it is easier to lift the pile of books by pressing the other end of the plank than
lifting the pile directly by one hand.
In this experiment, plank acts as a lever, wooden block as a fulcrum, pile of books is the load and
eff ort is applied by the hand.

Levers are categorised under three diff erent classes. This classifi cation is based on the
positions of fulcrum, load and eff ort in diff erent cases.

load
loa
eff ort load
In class one levers, the fulcrum is in
between the eff ort and the load. Scissors,
f
fulcrum
pliers and see-saw are examples of class
fulcrum
one levers.
eff ort
Class one lever

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