Introduction to Force, Work and Energy
We often use the phrases force, work, energy, and power in ordinary conversation. A teacher instructing a class, a student studying for a test, a mother making meals, and a farmer ploughing the field are all considered to be at work. A person with high stamina or energy can work for lengthy periods of time. In karate or boxing, we talk about forceful punches delivered quickly. In this article, we will talk about force, work and energy and also about the work power energy formulas.
Force and Its Types
A push or pull on an object is referred to as force. Force is utilised not just to move but also to halt an object. Force is used to affect an object's direction and position. It has the ability to change the speed of a moving object.
(Image will be uploaded soon)
There are several types of forces and some of which are explained below:
Muscular Force: It is defined as any force applied by muscles such as the arms or legs.
(Image will be uploaded soon)
Frictional Force: The force exerted when two surfaces come into contact is known as friction. Friction acts on all moving things, however the force of friction always works in the opposite direction to the movement of the body.
(Image will be uploaded soon)
Gravitational Force: The force that pulls objects downwards towards the earth's core is known as gravity. It means all the objects try to move towards the centre of earth when allowed to fall freely.
(Image will be uploaded soon)
Mechanical Force: A mechanical force is defined as a force that involves direct contact between two things and resulting in a change in the state of the objects.
(Image will be uploaded soon)
What is Work?
Work is defined as everything that exhausts us, such as running, writing, art, and so on. The term "work" refers to both mental and physical labour. As a result, work is said to be done when a constant force is given to an object, causing the object to move in the same direction as the force.
The formula of work is given as:
$W=Fd$
Here,
$F$ = constant force
$d$ = displacement of the object
(Image will be uploaded soon)
Energy and Its Types
Energy can be defined as the ability of an object to do work. It is of two types:
Kinetic Energy: It is the energy possessed by an object due to its motion. For example, if a boy is running then it possesses kinetic energy. Mathematically, we can write the kinetic energy expression as:
$K.E.=\dfrac{1}{2}mv^2$
Here,
$m$ = mass of the moving body
$v$ = velocity of the body due to its motion
Potential Energy: The energy of the body possessed by virtue of its position is known as potential energy. Mathematically, we can express the potential energy as
$P.E.=mgh$
(Image will be uploaded soon)
Power
It is defined as the ratio of work done and time. Mathematical, we can write it as
$P=\dfrac{W}{t}$
Here,
$W$ = work done
$t$ = time during which work is done
(Image will be uploaded soon)
Work Energy Principle or Work Energy Theorem
According to this principle, the amount of work done by a body is always equal to the change in kinetic energy of the body. Mathematically, we can write it as
$W=\Delta K=\dfrac{1}{2}mv^2_f-\dfrac{1}{2}mv^2_i$
Here,
$\Delta K$ = change in kinetic energy,
$v_i$ = initial velocity of the body,
$v_f$ = final velocity of the body.
Solved Questions
What are the units of work and energy?
Ans: The standard units of measurement for work and energy are the same i.e, Joule (J). As work can be written as a product of force and displacement, so we can also write the unit of work as Newton metre.
What is the difference between force and energy?
Ans: A force is any activity that tends to change a body's condition of rest or motion. Energy is a system attribute that measures a system's ability to accomplish work, for example potential and kinetic energy.
While catching a cricket ball of mass 100 g moving with a velocity of 10 m/s. find the work done in catching the ball.
Ans: Given:
The mass of the ball, $m$ = 100g = 0.1 kg
Initial velocity of the ball, $v_i$ = 10 m/s
Final velocity of the ball, $v_f$ = 0………(As ball get stopped after catching it)
Now applying the concept of work energy principle,
$W=\dfrac{1}{2}mv^2_f-\dfrac{1}{2}mv^2_i$
After putting the values of the quantities, we get:
$W=\dfrac{1}{2}\times (0.1) (0)^2-\dfrac{1}{2}\times (0.1) (10)^2$
$W= 0- 5=-5J$
Hence, the amount of work done in catching a ball is -5J.
Fun Facts
Everything around us is controlled by some kind of force, for example, the revolution of Earth around the Sun and Moon around the Earth is done in a proper orbit because of the presence of gravitational force.
You are able to write on paper because of the presence of frictional force.
Summary
In this post, we have mentioned various concepts like work, force and its types, energy and its types and also about the concept of power. We have discussed the concept of work energy principle and also solved numericals on work energy theorem.
Learning By Doing
At the railway station, you have noticed the coolie is putting up the luggage on his head. In that case, think about whether the work is done or not. If not then why?
FAQs on Concept of Force Work and Energy
1. What is a force in simple terms?
A force is simply a push or a pull on an object. It is what can cause an object to start moving, stop moving, change its speed or direction, or even change its shape. For example, when you kick a football, you apply a force to it.
2. What is meant by 'work' from a scientific point of view?
In science, work is done only when a force applied to an object causes it to move over a distance. If you push a heavy box and it slides across the room, you have done work. However, if you push against a solid wall and it doesn't move, no work is done on the wall, even if you feel tired.
3. What is energy, and can you give some examples of its different forms?
Energy is the ability or capacity to do work. Nothing can happen without energy. It exists in many forms. The most common types are:
- Kinetic Energy: The energy of a moving object, like a rolling ball.
- Potential Energy: Stored energy due to an object's position, like a stretched rubber band.
- Heat Energy: The energy that makes things warm.
- Light Energy: The energy that allows us to see.
4. How are force, work, and energy connected to each other?
Force, work, and energy are fundamentally linked. You must use energy to apply a force. When that force successfully moves an object, work is performed. Therefore, work can be described as the transfer of energy from one thing to another by applying a force.
5. Is it possible for energy to be destroyed?
No, energy cannot be created or destroyed. This is a fundamental rule in science known as the Law of Conservation of Energy. Energy can only be changed, or transformed, from one form into another. For example, when you switch on a fan, electrical energy is transformed into kinetic energy (the moving blades) and sound energy.
6. What is the main difference between potential energy and kinetic energy?
The key difference is that potential energy is stored energy that an object has because of its position or state, while kinetic energy is the energy an object has because it is in motion. A book held high in the air has potential energy. If you let it go, that potential energy is converted into kinetic energy as it falls.
7. Why does a rolling ball eventually stop on its own?
A rolling ball stops because of a force called friction. Friction is a force that opposes motion when the ball's surface rubs against the ground. This force converts the ball's kinetic energy (energy of motion) into other forms, primarily a tiny amount of heat energy, causing the ball to slow down and eventually stop.
8. Can work be done without an object moving?
No, according to the scientific definition, for work to be done, there must be displacement (movement) in the direction of the applied force. Even if you exert a massive force on an object, if it does not move from its position, the work done on that object is considered to be zero.
