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## Physics / Forces and Resources

### Physics / Forces and Resources

Machines are the devices which make our work easier and faster.

1) Machines helps in gaining force. With the help of machines, small force can be used to overcome a large force e.g. screw jack can lift an object as heavy as car to change its tyres.
2) Machine can change the direction of the force so that force can be applied in a more convenient manner e.g. rope passing over a wheel make easy to lift water from well.
3) Machines helps in carrying out unsafe and dangerous tasks e.g. pair of tongs can be used to lift a piece of burning coal from fire.

• Learn about simple machines and their different types - Lever, Inclined plane, Screw, Wheel and axle, wedge, pulley.
• Learn about terms that are used in simple machines -

Effort: An effort is the force applied to a machine to do mechanical work.
Load: Load is the force that a machine exerts on a given body to be moved.
Fulcrum : A fixed point about which the machine can turn. Mechanical advantage of the lever = MA = effort arm/ load arm.

• Find out to which class lever do the following object belongs- Scissor, Nut cracker, Seesaw, Wheel barrow, Fishing rod.
• Learn how principle of inclined plane is used in screw and learn to make your own simple machines.

Force

• Force is a physical cause that changes or may tend to change the state of rest or the state of motion of an object. Force comes into play due to interaction of two or more objects.
• Force is any influence that causes an object to undergo a change in speed, a change in direction, or a change in shape.
• Combined forces - Forces applied on an object in the same direction add to one another. If the Forces acting in opposite directions on an object, the net force acting on it is the difference between two forces.

Pressure is force per unit area applied in a direction perpendicular to the surface of an object. The perpendicular force applied is called thrust. Pressure = force/area SI unit: Pascal, denoted by Pa
The two important factors on which pressure depends are - Force and Area.

Learn practical applications of pressure in daily life -School bags have wider straps ,It is easier to walk on a sand with flat shoes rather then shoes with sharp heels. Understands the atmospheric pressure. The atmospheric air extends up to many kilometres above the surface of the earth. The pressure exerted by this air is known as atmospheric pressure.

Energy is the capability of doing work. Enjoy interesting facts about different forms of energy.
Law of conservation of energy- "Energy can neither be created nor be destroyed , but can be converted from one form to another. e.g. Sun is prime source of energy and its energy is converted to different forms".
Learn how energy flow takes place in nature and what is its importance.
Know about renewable and non-renewable sources of energy - Find out the various techniques to conserve the non renewable energy resources- coal, petroleum, natural gas, nuclear energy by using renewable energy - solar energy, wind energy, ocean energy, geothermal energy .
By encouraging conservation, increasing investments in clean, renewable sources of energy, and promoting increased domestic production of oil and gas, we can build a more secure future for our country.

Exercises
Topics
Exercises
Topics
• ### Moments and Levers - SmartTest

SmartTest on Moments and Levers

• Questions: 10

### Force - SmartTest

SmartTest on Force

• Questions: 10

### Friction - SmartTest

SmartTest on Friction

• Questions: 10

### Work and Energy - SmartTest

SmartTest on Work and Energy

• Questions: 10

### Energy sources - SmartTest

SmartTest on Energy sources

• Questions: 10

### Pressure and Liquid Pressure - SmartTest

SmartTest on Pressure and Liquid Pressure

• Questions: 10
• Moments and levers
• Centres of mass