Notes
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Topics to be learn : Simple machines
Maintenance of machines |
Machines : Devices which are used to get more work done in less time and less effort are called machines.
- By the use of machine, we can finish the work in less time and with less effort.
- If machines are not used, we require more time and more effort to complete even the simple tasks.
Simple machines : Machines having one or two parts and a simple and easy structure are called simple machines.
- Examples : The nail cutter, the bottle opener, the wheel used to push the load are all machines. They have only one or two parts and a simple and easy structure.
Complex machines : Machines having many parts which carry out many processes for completing a task are called complex machines.
- Examples : Motor bike, Mixer, Sewing Machine, Bicycle etc. These machines have many parts which carry out many processes for completing a task. For this purpose, the parts are joined to one another.
We use simple as well as complex machines depending upon the task that we want to carry out. We also choose the machine as per the available time and efforts required for completing that task.
Simple machines - examples :
An inclined plane : To load a heavy drum onto a truck, different methods can be used. In this activity, a plank was used.
Archimedes screw : It is a simple machine which was discovered by the great scientist Archimedes.
A wedge : When two inclined planes are joined to form a sharp tool, it is called a wedge.
- Examples : An axe, a knife, a chisel, a needle, a nail are all different types of wedges.
A lever ; The lever is a type of simple machine which has three parts. viz. effort, load and fulcrum There are three types of levers depending upon the positions of the effort, the fulcrum and the load. To understand the working of the three types of levers, we can perform some simple experiments.
Pulley :
Q. A needle is required for stitching cloth, We use knife for cutting fruit. If the tip of a needle or the edge of a knife becomes blunt, then the needle does not penetrate the cloth and the knife does not cut into the fruit. Why is this so ?
Ans. If the needle becomes blunt or the edge of the knife loses sharpness, we need to put more force while using these. The frictional force also rises and therefore we cannot expect the same work from these equipment. Hence the needle as well as knife will not function the way they are supposed to work.
Maintenance of machines :
It is very important to take care of the machines otherwise we may not be able to use them efficiently.
Machines are damaged due to the following reasons :
- Parts of the machine rubbing against each other due to continuous use.
- Parts affected by weather and dust, they rust and erode.
- Damage of the machine due to wear and tear.
Following measures should be taken to maintain the machines :
If we do not maintain the machines properly, they will be not of any use when we actually need them.
Machines should be handled properly and with care so that there are no accidents.
Big factories have a separate department for the maintenance of machines.
Factories are closed at regular, fixed periods for the maintenance of machines.