A comprehensive note on absolute Gravitational potential energy and gravitational potential
and why these both is negative for A Level and grade 12 physics students (1)
first we have to understand positive and negative work and potential energy
positive work
when force F acting on a body of mass m and displacement d covered by the body both are in the
same direction, it will be defined as positive work and it always increases the energy of the body or
the system.
Negative work
when force F acting on a body of mass m and displacement d covered by the body both are in the
opposite direction, it will be defined as negative work and it always decreases the energy of the body
or system.
Potential energy :
we know that the kinetic energy of a body is defined as 1/2 and the body will have this value of
kinetic energy everywhere in the universe. But a body will have some potential energy, only when it
is feeling the presence of the other body, or it is in the interaction or influence of other body. So when
a body is at a very large distance from the centre of the earth and the force of gravity on it becomes
zero. Its potential energy also becomes zero. And we will say that the body is at infinite distance from
the center of the earth.
Definition
The absolute gravitational potential energy of body at a point is defined as the work done in
bringing a body of mass m from infinity (where the gravitational force is zero) to the point under
consideration
Explanation
Let the Mass of earth be M, and body of mass be m is at very large distance (infinity) at point A
from the centre of the earth where gravitational force on the body becomes zero. Now the work is
done (some external body does work on m) on the body in moving it from point A to point B at
distance r from the centre of the earth, and let the gravitational force on m at point B be F which will
have some value greater than zero.
When the body is being moved from point A to point B. Our
Applied force Fa is in opposite direction to the force of gravity
F on the body . both forces are kept equal in magnitude but opposite in direction
and why these both is negative for A Level and grade 12 physics students (1)
first we have to understand positive and negative work and potential energy
positive work
when force F acting on a body of mass m and displacement d covered by the body both are in the
same direction, it will be defined as positive work and it always increases the energy of the body or
the system.
Negative work
when force F acting on a body of mass m and displacement d covered by the body both are in the
opposite direction, it will be defined as negative work and it always decreases the energy of the body
or system.
Potential energy :
we know that the kinetic energy of a body is defined as 1/2 and the body will have this value of
kinetic energy everywhere in the universe. But a body will have some potential energy, only when it
is feeling the presence of the other body, or it is in the interaction or influence of other body. So when
a body is at a very large distance from the centre of the earth and the force of gravity on it becomes
zero. Its potential energy also becomes zero. And we will say that the body is at infinite distance from
the center of the earth.
Definition
The absolute gravitational potential energy of body at a point is defined as the work done in
bringing a body of mass m from infinity (where the gravitational force is zero) to the point under
consideration
Explanation
Let the Mass of earth be M, and body of mass be m is at very large distance (infinity) at point A
from the centre of the earth where gravitational force on the body becomes zero. Now the work is
done (some external body does work on m) on the body in moving it from point A to point B at
distance r from the centre of the earth, and let the gravitational force on m at point B be F which will
have some value greater than zero.
When the body is being moved from point A to point B. Our
Applied force Fa is in opposite direction to the force of gravity
F on the body . both forces are kept equal in magnitude but opposite in direction
