What is Energy , If you want to know simple meaning. Then first you need to understand, law of conservation of energy. Because it has many form. But this is divided into two types of energy .which is kinetic energy and potential energy.
Can you tell, which body has energy. Let me explain, A agent which can apply force has energy. If that agent has capacity to apply force, then you can say that agent has energy.Because applying force and making displacement is doing work. So anything which can do the work has energy.
Hence it is not necessary agent do the work all the moment. But it possess energy. So take an example to understand it. Suppose a bottle has petrol. Here petrol is simply into the bottle but not doing any work. So it does not mean petrol has not energy. If the same petrol is fill into the motorcycle, Then motorcycle engine is start and apply a force on motorcycle piston.
And due to this petrol a force is applied on motorcycle. Therefore motorcycle moves and do the work. But it is important if you don’t fill the petrol into the motorcycle. Then motorcycle will not move. Hence it does’t do any work. So it is clear that,which has capacity to do work motorcycle or petrol. Obviously your answer is petrol.
So from above explanation. I hope you have got the concept what is energy. And you can say “Energy is capacity to do work”. Therefor motorcycle does’t has energy. Petrol has energy because it has capacity to do work.
Hence motorcycle is a device. Which take energy from petrol and converted into other form like heat. And the process of energy conversion is work done. So energy does the work. If a body or anything, which has no energy. Then it can’t do any work.
Energy is invisible and has many forms like light hear, sound, wave. But which has mainly two category kinetic and potential.Hence it can transform one category to other category. And it can also change one form to other form as well. But important point to remember, energy can’t be created or destroyed. This property of energy is called, law of conservation of energy.
Kinetic energy is a form of energy, when a object or particle is in motion. Hence Can you tell me, where does this kinetic energy comes from. Well this comes from the potential energy that an object or particle has. So kinetic energy is the capacity to do work.
Hence from the above picture . What do you think about kinetic energy ? Does it depends upon frame of reference ? Yes kinetic energy depends upon frame of reference. Let me explain.
You know formula of kinetic energy is mV²/2. Now from the above picture. If train is moving with velocity V, then kinetic energy of train is mV²/2. Where m is mass including with person A and B. Therefor what is kinetic energy of A and B with respect to trail ?
Obviously it is zero. Because with respect to train both person A and B are sitting. They are not moving or not changing their position. But with respect to person C sitting on the ground. Both A and B are moving with same speed of train.
Hence their kinetic energy is MaV²/2 and MbV²/2. So it is clear. When you change the reference frame. Same person kinetic energy is different. Therefore kinetic energy depends upon frame of reference.
Potential energy is the energy, which is stored energy due to its position. So initial and final position is consider for potential energy. Therefore potential energy can be negative, positive or zero. Do you know ? where does this energy comes from ? Well this energy comes from work done on object.
Why potential energy is called stored energy ? Well this is Because of it is used in future. If you do some work and if kinetic energy is not change. Then what do you think, where does this work gone. Does this stored in potential energy. BIG no let me explain this. Suppose you are pushing a block on floor surface here and there. And finally block is stopped, then block kinetic energy is now zero.
I hope you are agree ? Because block final velocity is zero. Also block potential energy is not changed. Because potential energy is define for very special force. It is not define for all forces. Hence do you know conservative force ? let me explain.
Therefore for conservative force, work done does not depend on path taken. Such types of force is called conservative force. And potential energy has only meaning for conservative forces. So friction is not a conservative force . Hence work done by friction force is not stored in potential energy.
Therefore friction force work done is dissipated, in the form of heat and sound energy.
Mechanical energy is define as sum of kinetic and potential energy. Which is used to do work. Hence in other words, it is energy in an object due to its motion or position or both. When the work is done upon the object. Therefore that object gains energy. The energy received by the object, due to work done is called Mechanical Energy.
Mechanical energy can be either kinetic energy (Energy of motion) or potential energy (Stored energy of position). From the above picture moving mass M possesses Mechanical energy due to its motion (Kinetic energy). Therefore a moving ball possesses mechanical energy, due to both its high speed (kinetic energy) and its vertical position above the ground (gravitational potential energy).
For more information about What is Energy concept, you can refer my previous post given link below.
I will continue in next post with more hidden concept of Physics. And i hope you have enjoyed learning What is Energy ?. So you are most welcome for your feedback, comment and share. Learn more new Tips and grow. Thanks for sharing.