Page 123 - Viva ICSE Science 5 : E-book

Screw

A screw is an inclined plane wrapped around a rod spirally.
conical rod
It is commonly used for holding things together and lifting
materials. Using screws, two things can be interlocked in ridges
(narrow inclined plane
such a way that they cannot be forced to separate. Screws wrapped around a cylinder)
are also used as a method of lifting things like in a jack. Screw

Wedge
axe
wedge A wedge is a triangular-shaped simple machine
shape
which has slanting edges that meet to form a
sharp edge at one end. It is made up of metal,
wood or stone. It may be attached to a handle
at the thicker end. The sharp edge is used to

break or cut materials by applying force using
the handle. Some common examples of wedges
Example of wedge
are axes, knives and our teeth.

TERMS TO KNOW

1. Machine: A device or a tool which helps us to do a work easily by reducing the time and the
amount of force
2. Lever: A simple machine in which a rigid bar or rod rests on a support and is used to lift
heavy weights with minimum amount of eff ort
3. Inclined plane: A sloping or a slanting surface which connects a lower level to a higher level
4. Pulley: A simple machine made with a rope or chain wrapped around a wheel
5. Wheel and axle: A simple machine in which a large wheel rotates around the centre called
axle
6. Screw: An inclined plane wrapped around a rod spirally
7. Wedge: A triangular-shaped simple machine which has slanting edges that meet to form a
sharp edge at one end

QUICK LOOK

1. A machine is a device or a tool which helps us to do a work easily by reducing the time
and the amount of force.
2. Machines are of two types—simple (like lever and pulley) and complex (like scooter and
washing machine).
3. There is a wide range of simple machines. The most common simple machines are lever,
inclined plane, pulley, wheel and axle, screw and wedge.

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