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Work
Work refers to an activity that involves movement of the object when force is applied on it. For example, work is done when a person pushes a car and the car moves.

The formula of work is:

Work = Force distance

It means that more work is done, if more force is applied to an object, or the object moves larger distance, or both.

If a force is applied on an object, but no motion takes place then no work is done. For Example, if a person pushes against a wall, then no work is done unless the wall moves in the direction in which it is pushed.

The unit of measurement of work is unit of force multiplied by the unit of distance i.e.

Newton metre (Nm) or Joule (J).

For example, if a stone is pushed with the force of 5 N and it travelled a distance of 3 meter, the work done is 15 Nm or 15 J.

 

Force
A push or pull acting on an object is called a force.
A force can be used to:

  • Move a stationary object
  • Stop a moving object
  • Make a moving object move faster
  • Slow down a moving object
  • Change the direction of a moving object
  • Change the shape and size of an object

 Fig: Force exerted by two boys Fig: Force exerted by two boys 

Types of Force
There are different types of force:

Muscular Force
Muscular force is applied when we push, pull or lift something with our hand.

Fig: Muscular ForceFig: Muscular Force

Gravitational Force
Gravitational force or gravity is the force that attracts objects to the centre of the earth
Because of gravitational force, we are able to stay on the ground.

Fig: Gravitational ForceFig: Gravitational Force
Frictional Force
Frictional force is a force of resistance that tries to stop the movement of objects across a surface. On smooth surfaces less friction is exerted and on rough surfaces more friction is exerted. Due to it we are able to walk.

Fig: Frictional ForceFig: Frictional Force


Elastic Force
Elastic force arises when a body deforms. When we stretch a rubber band it regains its original position because of elastic force.

Fig: A picture showing stretching causes elasticity.Fig: A picture showing stretching causes elasticity.

Mechanical Force
Mechanical force is used by most of the simple machines. A wedge uses mechanical force to separate two objects.

Fig: Mechanical ForceFig: Mechanical Force

Buoyant Force
Buoyant force is the upward push of water on a floating object. When we push a mug or piece of wood in water, we can feel an upward thrust.


Fig: Buoyant ForceFig: Buoyant Force

Energy
Energy is the capacity or ability to do work. Energy can exist in different forms such as mechanical energy, heat energy, chemical energy, sound energy, muscular energy, solar energy, wind energy, etc.

Forms of Energy
Mechanical energy: Mechanical energy of an object is its energy due to its position or its motion or both. Mechanical energy is classified into potential energy and kinetic energy based upon its source of origin.

Potential energy of the object is its energy due to its position. For example, a book on a table before it falls possesses potential energy.
Heal energy: A heated substance possesses heat energy. For example, burning wood possesses heat energy. Heat energy is used to move steam engines. 

Fig: Heat EnergyFig: Heat Energy


Chemical energy: Chemical energy is the energy released or absorbed during a chemical reaction. For example, battery possesses chemical energy. 

Fig: Chemical EnergyFig: Chemical Energy

Sound energy: Energy possessed by sound wave is called sound energy. For example, sound from a music player possesses sound energy. 


Fig: when someone plays guitar, the strings vibrate and transmits energy.Fig: when someone plays guitar, the strings vibrate and transmits energy.

Muscular energy: Energy possessed by the muscles is called muscular energy. For example, a boy uses his muscular energy to lift dumbbell.

Fig: Muscular energyFig: Muscular energy

Solar energy: Energy possessed by sunlight is called solar energy. For example, solar energy is used by plants to produce foods.

Fig: Solar energyFig: Solar energy

Wind energy: Energy possessed by wind is called wind energy. For example, wind energy is used for drying clothes or moving wind mill. 

Fig: Wind EnergyFig: Wind Energy

Electrical energy: Energy possessed by electricity is called electrical energy. For example, a fan runs with electrical energy. 

Fig: Electrical energy possessed by fanFig: Electrical energy possessed by fan

Law of conservation of energy
The law of conservation of energy states that energy can only be transformed, it cannot be created or destroyed.
The international unit of energy JOULE is named in the honour of scientist James Prescott Joule.

Simple Machines
Machines are simple tools which make our work easier and faster. They help us to do many works.
Some examples of simple machines are lever, inclined plane, wheel and axle, pulley and screw.

Levers
Levers are commonly used tools like scissors, hammers and screw drivers.
When we lift a rock with the help of a rod, the weight lifted by the person is the load and the the force with which it is lifted is the effort. The point of contact of rod and the stone is the fulcrum.

Fig: A LeverFig: A Lever
Levers can be classified into the followings according to the position of the fulcrum, the load and the effort:
First class lever — when the fulcrum lies between the load and the effort, it is called first class lever. For example, see saw, scissors, etc.

Fig: First Class LeverFig: First Class Lever

Second class lever — when the load lies between the fulcrum and the effort, it is called second class lever. For example, a wheel barrow, a bottle opener. 

Fig: Second Class LeverFig: Second Class Lever

Third class lever - when the effort lies between the fulcrum and the load, it is called third class lever. For example, a stapler, a pair of tongs. 

Fig: Third Class LeverFig: Third Class Lever

Inclined Plane
An inclined plane is a slope which makes work easier. When workers have to load or unload a truck they use a plane of wood as an inclined plane.

Fig: An inclined planeFig: An inclined plane

The Pulley

A pulley is a small wheel with a groove around its outer edge. There are two types of pulleys: fixed pulley and movable pulley. The pulley used for drawing water from a well is a fixed pulley Movable pulleys along with fixed pulleys are used to lift loads.

Fig: A pulley pulled by a rope.Fig: A pulley pulled by a rope.

The Wheel and Axle

A wheel attached to a rod (called axle) is known as a wheel and axle arrangement. It is easier to push a load on wheels than carrying it. This arrangement is used in vehicles, sewing machines and cycles.

Fig: Wheel and Axle Fig: Wheel and Axle 


The Screw

Screw is a tool used to hold things tightly together. Bigger screws, called screw jacks, are used to lift cars and other heavy objects. When two things are joined by a screw, they are held together through a long distance while when we join things with a nail.

Fig: A ScrewFig: A Screw


      

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FAQs on Work, Force, Energy and Simple Machines - Additional Study Material for Class 5

1. What is work in the context of physics?
Ans. In physics, work is defined as the amount of energy transferred by a force acting through a distance. It is calculated by multiplying the force applied to an object by the distance the object moves in the direction of the force.
2. What is force and how does it relate to work?
Ans. Force is a push or pull that can change the motion or shape of an object. In the context of work, force is required to do work. Without a force acting on an object, no work can be done. The amount of work done is directly related to the magnitude and direction of the force applied.
3. What is energy and how is it related to work?
Ans. Energy is the ability to do work. In the context of work, energy is required to perform work. When work is done on an object, the energy is transferred from the source of the force to the object. The work done on an object is equal to the change in its energy.
4. What are simple machines and how do they help in performing work?
Ans. Simple machines are basic mechanical devices that can change the magnitude or direction of a force to make work easier. They include levers, pulleys, inclined planes, screws, wedges, and wheels and axles. By utilizing these simple machines, one can apply a smaller force over a longer distance to accomplish a larger force over a shorter distance, making tasks easier to perform.
5. How do simple machines affect the amount of work done?
Ans. Simple machines can make work easier by reducing the amount of force required to perform a task. They achieve this by increasing the distance over which the force is applied or by changing the direction of the force. By using simple machines, the force required to perform a task can be decreased, resulting in less work being done.
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