Page 125 - Viva ICSE Science 5 : E-book

3. Lever is a rigid bar or rod that rests on a support called _________.
(a) fulcrum (b) load (c) eff ort

4. Which of these is a modifi ed lever of the fi rst class?
(a) Wedge (b) Fixed pulley (c) Wheel and axle

E. Answer the following questions.

1. Defi ne a machine.

2. Write a short note on lever with a neat diagram.
3. Diff erentiate between the three classes of levers. Draw diagrams and give

examples of each class of lever.

4. How is an inclined plane useful to us?
5. What is a pulley? How does it help to lift things to some height?

6. Defi ne fi xed and movable pulleys with examples.

7. Explain the wheel and axle arrangement. What are its uses?

8. What is a screw? Mention its uses.

THINK AND ANSWER

1. The fl oors of the washrooms are inclined plane. Explain.

2. Name the simple machines that you would use to do the following tasks.
a. To open a door
b. To hold two things together
c. To cut a tree
d. To carry a load up to some height

TALK ABOUT

It is true that machines make our work easier. But it is also important to not depend entirely on
machines for simple works that can be done manually. Discuss.

LINK AND LEARN

Using the Internet, find out about the 'Ancient Machines'. Make a report on any five such machines.
Paste their pictures and write their uses.

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