STD6 TH SUB SCIENCE Lesson 8 Simple Machines

STD-6 TH SUB - SCIENCE Lesson - 8 Simple Machines Mr. kamble sachin kalyan-(Asst. Teacher) Narayanrao Sanas Vidyalay, Wadgaon khurd, Pune-41

WHAT IS MEANT BY SIMPLE MACHINES? v Such devices with a simple structure are called simple machine. s.

INCLINED PLANES An inclined plane is a flat surface that is higher on one end. Inclined planes make the work of moving things easier.

SCREW ØA Screw is an inclined plane wrapped around a shaft or cylinder. ØThe inclined plane allows the screw to move itself when rotated.

PULLEY Pulley are wheels and axles with a groove around the outside. A pulley needs a rope , chain or belt around the groove to make it do work.

Screw Inclined Plane Wrapped around post = Screw A Screw is really an Inclined Plane wrapped around a center post.

Single Fixed Pulley This pulley provides the user Directional Advantage, allowing someone to pull down to lift the load up. Is Mechanical Advantage provided with this system? No, the effort needed to lift this load is equal to the weight of the load. This is because the load is supported by only 1 rope arm. You must also pull an amount of rope equal to the height you wish to lift the load

LEVERS-FIRST CLASS In a first class lever the fulcrum is in the middle the load and effort is an either side. Think of a see-saw.

LEVERS- SECOND CLASS In a second class lever the fulcrum is at the end, with the load in the middle. Think of a wheelbarrow.

LEVERS-THIRD CLASS In a third class the fulcrum is again at the end , but the effort is in the middle. Think of a pair of tweezers.

WHEELS AND AXLES The wheel and axle are a simple machine. The axle is a rod that goes through the wheel which allows the wheel to turn. Gears are a form of wheels and axles.

Levers Quiz Use the following slides to quiz yourself on how well you can match commonly used items with their correct class of lever.

F A Class 1 Lever has its fulcrum between the effort and the load.

L A Class 2 Lever has its load between the effort and the fulcrum.

E A Class 3 Lever has the effort between the load and the fulcrum.

SIMPLE MACHINES � Simple Machines can be put together in different ways to make complex machinery

Assignment Q. 1 Answer the follwing : 1) What are simple machines? Give examples. 2) What is meant by a pulley? 3) What is meant by a lever? 4) What can you use as an inclined plane? 5) Give the examples of different types of levers.

Fill in the blanks. 1. The inclined plane is a ……………. Machine. 2. The wheel and its ………. . form a simple machine. 3. The sewing machine is a ………… machine.

Complete the following table Type of lever Positions of load, force and fulcrum Examples First order Force Fulcrum Load 1) Beam balance 2) To lift up a big stone by crow bar. Second order Fulcrum Load Force 1) Bottle opener 2) Wheel barrow Third order fulcrum force load 1) Lifting up the weights with hand 2) Fishing rods that anglers use.

T N A H O Y K ! U