A machine is any tool or device that enables us to do work easily, quickly and conveniently.
A simple machine is a tool that allows us to use less force to do work. There are seven types of simple machines.
1. Inclined planeAn inclined plane makes the job of moving loads from the lower to higher area or vice versa easier. For instance, pushing a heavy box to a higher area needs less effort than carry it up.
2. Screw
A screw has ridges called thread, cut around it in the form of a spiral and special kind of inclined plane. When a turning force is applied to the head of the screw, the spiral edge of the screw travels a longer distance. This implies that the force was applied over quite a long distance to make the screw moves forward at a very small distance.
3. Gear
Wheels with notches and cogs, cut around the edge is called gears. Each gear is fitted to another gear to transfer movement in a machine. A gear is also used to changed the direction and speed of a movement.
4. Pulley
A pulley is made up of wheel with groove round a rim of the pulley which holds a rope. A rope or pulley does not increase the lifting force but it only changes the direction of force. The force of pulling is equal to the weight of the load.
5. Lever
A lever is a rigid bar or rod or plank that can swing around a support to transmit and magnify a force which is used to lift a load. The support or point on which the lever turns is called fulcrum. The object that the lever lifts or moves is called load. The force that is exerted on the lever is called effort.
6. Wedge
When one or two incline planes are put together, back to back, it forms a wedge. A wedge changes the direction of a force and increases the effort. For example, using a sharp knife to cut sweet potato. As the knife moved downwards it creates a strong sideways force that spilts it open.
7. Wheel and axle
Wheel is a cylindrical object or circular object that rotates about the axis of the cylinder. The axle is a rigid rod that goes throught the centre of the wheel and lies along the culinder axis. When the two are combined together, it is called a wheel and axle.
Vocabulary
ENGLISH | BAHASA MELAYU |
complex machine | mesin kompleks |
daily chores | kerja harian |
hand drill | gerudi tangan |
Inclined plane | satah condong |
lever | tuas |
load | beban |
pulley | takal |
screw | skru |
simple machine | mesin ringkas |
thread | bebenang |
wedge | baji |
wheel and axle | roda dan gandar |
Before ending this lesson, let' s do some tests.
TEST B - MACHINES
For each of the following complex machine, tick (√) the simple machines found in them.
No | Complex machine | Simple machines found in them | ||||||
L = Lever WA = Wheel and axle IP= Inclined plane P = Pulley S = Screw W = Wedge G = Gears | ||||||||
L | WA | IP | P | S | W | G | ||
1 | A pair of scissors | |||||||
2 | A bicycle | |||||||
3 | A manual can opener | |||||||
4 | A wheelbarrow | |||||||
5 | A lawn mover | |||||||
6 | A hand drill | |||||||
7 | A G-clamp | |||||||
8 | A hole puncher | |||||||
9 | A step ladder | |||||||
10 | A tower crane |
Have a good try!
Yes, it makes works easier!
ReplyDeleteThank you for viewing, Jing Yee.
ReplyDeleteI have put in some exercises for this topic, You might try to answer.
Here are the answers :
ReplyDelete1. √
2. X
3. √
4. √
5. X
6. √
7. X
8. X
9. √
10. X
How many correct answers do you get?
I have changed the true or false questions into another form of question as TEST A and added in TEST B. It is more challenging, try it!
ReplyDeleteI think the students should try out those simple machines, because this may help them alot in their daily lifes instead of playing the meaningless computer games or video games and watching those dramas that could mislead their thinking easily... =)
ReplyDeleteKoo, you are right, I agree with you.
ReplyDelete