physics abc about energy 01

Physics ABC - About Energy 01

2021-06-03

Energy, Work, Gravitational Potential, Kinetic Energy. Conservation of Energy, Efficiency and Power.

What is Energy?

Energy is a measurement of the ability to do work. It is the quantitative property that must be transferred to a body or physical system to perform work on the object, or to heat it. (from Wikipedia)

What is Work?

Work is the energy on an object via a force application along a displacement. Work causes a change in energy in that object.

Energe and Work

W = ∆E (Work is the change of Energe)

W = Fs * cosA

It means: Work = Force x displacement x Cos(Angle).

W = Fs (When the angle is 0, which mean the force and the displacement have the same direction)

The unit is Joule(J)

1 Joule = 1N * m = 1kg * m /s² * m = 1kg * m² /s²

Both energy and work are scalar quantities. NO direction
Both energy and work are measured in units of Joule - J.
Zero work:
- If a force applies on an object but the object does not move. The work = 0J.
- If an object moves at a constant velocity, but with no force on it. The work = 0J.
- If a force is perpendicular to the motion of the object (90°), the work = 0J. (because cos90° is 0)
Positive work: Force assists with the displacement of object
Negative work: Force acts against the displacement of object
Net/Total work: The algebraic sum of the work done by individual forces.