Simple Machines - Class 5 Notes & Olympiad Questions

Simple Machines

Simple machines are tools that make our work easier by reducing the effort required to do a task. They are found in various tools, devices, and everyday objects.
They are easy to understand and use, and they can save us time and energy when we're doing various tasks.

Types of Simple Machines

Lever

a) A lever consists of a rigid bar or beam that can rotate around a fixed point called a fulcrum.
b) It has two main parts: the effort arm and the load arm. When a force is applied to one end (effort arm), it can lift or move a load on the other end (load arm).
c) There are three types of levers:

1. First-class lever: The load and effort are on opposite sides of the fulcrum. Examples include scissors, a see-saw, and a balance scale.

2. Second-class lever: The fulcrum and effort are on opposite sides of the load. Examples include a nutcracker, a bottle opener, door hinges, and a wheelbarrow.

3. Third-class lever: The effort is between the load and the fulcrum. Examples include forceps, a fishing rod, ice tongs, and a broom with a handle.

Pulley

a) A pulley is a grooved wheel with a rope or cable running along the groove.
b) It helps us lift or lower objects easily by pulling on the rope.
c) It can be fixed or movable.
d) A fixed pulley changes only the direction of the force, while a movable pulley allows you to multiply the force applied.
e) By combining multiple pulleys, you can create complex pulley systems.
f) Examples of pulleys include flagpoles, cranes, and window blinds, drawing water from a well.

Inclined Plane

a) An inclined plane is like a slanted flat surface.
b) It allows us to move heavy objects up or down with less force.
c) Examples of inclined planes are ladders, slides in a playground, stairs, and ramps.

Wheel and Axle

a) The wheel and axle is a combination of a wheel, which is a circular object, and an axle, which is a cylindrical shaft that goes through the centre of the wheel.
b) When force is applied to the wheel, it rotates around the axle.
c) Examples of wheel and axle include a bicycle wheel, a doorknob, and a steering wheel.

Wedge

a) A wedge is a triangular-shaped object with a thick end and a thin end. It is used to split, hold, or lift objects apart.
b) By applying force to the thick end, the wedge can exert a greater force on the object being split or lifted.
c) Examples of wedges include knives, axes, and doorstops.

Screw

a) A screw is an inclined plane wrapped around a cylindrical post. It consists of a threaded shaft and a head.
b) When the screw is rotated, it moves through a solid object or another threaded surface.
c) Screws are commonly used to hold things together or to lift heavy objects.
d) Examples of screws include bolts, screws used in woodworking, and jar lids.