LESSON 9 – SIMPLE MACHINES
I Keywords:-
1. Force
2. Machines
3. Ability
4. Work done
5. Inclined plane 6. Screw
7. Wedge
8. Pulley
9. Axle
10.Lever 11.Ramp 12.Grooves 13.Fulcrum 14.Resemble 15.Spear
II Define the following:-
1. Force: A push or pull applied on an object.
2. Energy: The ability to do work.
3. Machine: A tool or a device which makes our work easy.
4. Fulcrum ( ): The fixed point of the lever which gives support
and around which it moves.
5. Load ( ): The weight which is pulled or moved by the lever.
6. Effort ( ): The force applied to the lever to pull or move the
load.
III Answer the following:-
1. List six main types of simple machines.
Ans: The six main types of simple machines are
Inclined plane
Screw
Lever
Pulley
Wheel and Axle
Wedge
2. When do we say that work is done?
Ans: Work is said to be done when a force applied on a body makes the body move in the direction of force.
3. Briefly describe the following simple machines with a neat diagram.
a) Inclined plane: An inclined plane is a flat, slanting surface which connects lower level to a higher level. It helps to move or lift heavy things by using less effort or force. An inclined plane is also called a ramp.
Ex: Road going up a hill, slides, wheel chair ramps.
b)Screw: A screw is an inclined plane arranged in a spherical manner around a central pole or a rod. It has many grooves on it. A screw can hold things together and can be fixed with the help of a screw driver.
Ex: Bottle cap, Light bulbs, bolt.
c)Wedge: A wedge is a simple machine in which two inclined planes are joined each other back to back. It is used to cut things or split things apart.
Ex: Needle, spear, Knife.
d)Wheel and axle: It is a simple machine in which wheel is attached to a rod called axle. Rod passes through the centre of a wheel. The wheel rotates around the rod. It helps to move heavy object
Ex: Cars, trains, roll skates have a wheel and axle.
4. Define lever. List out the three types of levers with example.
Ans: Lever is a stiff bar that moves around a fixed point. There are three types of levers depending on the position of the load, the fulcrum and the effort.
a) First class lever: In this lever, the fulcrum is placed between the load and the effort.
Ex: see-saw, scissors, Physical balance.
b) Second class lever: In this lever, the load is between fulcrum and effort.
Ex: Nut cracker, Bottle opener, lemon squeezer.
c) Third class lever: In this lever, the effort is between fulcrum and the load
Ex: Tweezers, shovels, Fishing rod.
5. HOTS:-
Pulleys make our work easier. Justify.
Ans: A pulley is a simple machine which has a rope, string or chain going over a grooved wheel. It helps to perform work by changing the direction of forces and making easier in lifting or lowering heavy loads with less effort.
A pulley is of two types.
i) Fixed pulley (Flag pole, water well)
ii)Movable pulley (Construction cranes, Modern Elevators)
6. Value based question:-
Simple machines have made our life simple and easy. What value we can adopt from these machines?
Ans: Simple machines help us to do work with little energy and also within a limited period of time. These simple machines teach us that we can do maximum work by exerting less effort in the right direction.
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Answers
Answer:
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Answer:
- Define the following:-
- Force: A push or pull applied on an object.
- Energy: The ability to do work.
- Machine: A tool or a device which makes our work easy.
- Fulcrum ( ): The fixed point of the lever which gives support and around which it moves.
- load ( ): The weight which is pulled or moved by the lever.
- Effort ( ): The force applied to the lever to pull or move the load.
- Answer the following:-
1. List six main types of simple machines.
Ans: The six main types of simple machines are
- Inclined plane
- Screw
- Lever
- Pulley
- Wheel and Axle
- Wedge
2. When do we say that work is done?
Work is said to be done when a force applied on a body makes the body move in the direction of force.
3. Briefly describe the following simple machines with a neat diagram.
a) Inclined plane
An inclined plane is a flat, slanting surface which connects lower level to a higher level. It helps to move or lift heavy things by using less effort or force. An inclined plane is also called a ramp.
Ex: Road going up a hill, slides, wheel chair ramps.
b) Screw
A screw is an inclined plane arranged in a spherical manner around a central pole or a rod. It has many grooves on it. A screw can hold things together and can be fixed with the help of a screw driver.
Ex: Bottle cap, Light bulbs, bolt.
c) Wedge
A wedge is a simple machine in which two inclined planes are joined each other back to back. It is used to cut things or split things apart.
Ex: Needle, spear, Knife.
d) Wheel and axle
It is a simple machine in which wheel is attached to a rod called axle. Rod passes through the center of a wheel. The wheel rotates around the rod. It helps to move heavy object
Ex: Cars, trains, roll skates have a wheel and axle.
4. Define lever. List out the three types of levers with example.
Lever is a stiff bar that moves around a fixed point. There are three types of levers depending on the position of the load, the fulcrum and the effort.
a) First class lever:
In this lever, the fulcrum is placed between the load and the effort.
Ex: see-saw, scissors, Physical balance.
b) Second class lever:
In this lever, the load is between fulcrum and effort.
Ex: Nut cracker, Bottle opener, lemon squeezer.
c) Third class lever:
In this lever, the effort is between fulcrum and the load
Ex: Tweezers, shovels, Fishing rod.
5. Pulleys make our work easier. Justify.
A pulley is a simple machine which has a rope, string or chain going over a grooved wheel. It helps to perform work by changing the direction of forces and making easier in lifting or lowering heavy loads with less effort.
A pulley is of two types.
i) Fixed pulley (Flag pole, water well)
ii)Movable pulley (Construction cranes, Modern Elevators)
6. Value based question:-
Simple machines have made our life simple and easy. What value we can adopt from these machines?
Simple machines help us to do work with little energy and also within a limited period of time. These simple machines teach us that we can do maximum work by exerting less effort in the right direction.
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