when something was in rest position,there is any energy???? why????
Answers
first of all, being at rest and possessing potential energy are two entirely unconnected phenomena
if an object is at rest, its kinetic energy is defined to be equal to zero
so that as it moves and gains speed, the gain in kinetic energy is defined as the kinetic energy at that speed
as for potential energy, recall what was crammed into our heads the first time this word was introduced to us:
that, it is the energy that an object possesses by virtue of its position!
the single word disoriented us for ever
we ought to have been taught simultaneously that any position is relative to a certain coordinate system
where we set our origin, the zero
in you room, you may choose the floor as the origin
then, a glass on your study table, height h above the floor, possesses potential energy mgh
relative to the floor
the glass is resting on the table!
accidentally, the glass falls, hits the floor and smashes
there is sound and energy has certainly been needed in breaking the glass to pieces
where has it come from?
the potential energy that the glass had - since it was at a higher position -(remember the ‘by virtue of’ in the definition) kept converting into kinetic energy as it was falling until it made contact with the floor
the moment its motion was arrested by the hardness of the floor, this entire energy was utilised in making the noise and breaking the glass
nobody forces you to set the zero of potential energy at the floor
when you are studying, you can as well choose the zero of the potential energy on the study table also
then, an object that you hold in your hand above the table has potential energy +mgh while the one on the floor will have energy -mgh
just as in coordinate geometry you set your origin, your coordinate system and positive and negative sides
if an object is at rest, its kinetic energy is defined to be equal to zero
so that as it moves and gains speed, the gain in kinetic energy is defined as the kinetic energy at that speed
as for potential energy, recall what was crammed into our heads the first time this word was introduced to us:
that, it is the energy that an object possesses by virtue of its position!
the single word disoriented us for ever
we ought to have been taught simultaneously that any position is relative to a certain coordinate system
where we set our origin, the zero
in you room, you may choose the floor as the origin
then, a glass on your study table, height h above the floor, possesses potential energy mgh
relative to the floor
the glass is resting on the table!
accidentally, the glass falls, hits the floor and smashes
there is sound and energy has certainly been needed in breaking the glass to pieces
where has it come from?
the potential energy that the glass had - since it was at a higher position -(remember the ‘by virtue of’ in the definition) kept converting into kinetic energy as it was falling until it made contact with the floor
the moment its motion was arrested by the hardness of the floor, this entire energy was utilised in making the noise and breaking the glass
nobody forces you to set the zero of potential energy at the floor
when you are studying, you can as well choose the zero of the potential energy on the study table also
then, an object that you hold in your hand above the table has potential energy +mgh while the one on the floor will have energy -mgh