define these work. energy. power
Answers
Work is defined as a force causing the movement—or displacement—of an object. In the case of a constant force, work is the scalar product of the force acting on an object and the displacement caused by that force. Though both force and displacement are vector quantities, work has no direction due to the nature of a scalar product (or dot product) in vector mathematics. This definition is consistent with the proper definition because a constant force integrates to merely the product of the force and distance.
Examples of Work
There are many examples of work in everyday life. The Physics Classroom notes a few: a horse pulling a plow through the field; a father pushing a grocery cart down the aisle of a grocery store; a student lifting a backpack full of books upon her shoulder; a weightlifter lifting a barbell above his head; and an Olympian launching the shot-put.
In general, for work to occur, a force has to be exerted on an object causing it to move. So, a frustrated person pushing against a wall, only to exhaust himself, is not doing any work because the wall does not move. But, a book falling off a table and hitting the ground would be considered work, at least in terms of physics, because a force (gravity) acts on the book causing it to be displaced in a downward direction.
Energy is defined as the capacity of a physical system to perform work. However, it's important to keep in mind that just because energy exists, that doesn't mean it's necessarily available to do work.
Forms of Energy
Energy exists in several forms such as heat, kinetic or mechanical energy, light, potential energy, and electrical energy.
Heat - Heat or thermal energy is energy from the movement of atoms or molecules. It may be considered as energy relating to temperature.
Kinetic Energy - Kinetic energy is the energy of motion. A swinging pendulum has kinetic energy.
Potential Energy - This is energy due to an object's position. For example, a ball sitting on a table has potential energy with respect to the floor because gravity acts upon it.
Mechanical Energy - Mechanical energy is the sum of the kinetic and potential energy of a body.
Light - Photons are a form of energy.
Electrical Energy - This is energy from the movement of charged particles, such as protons, electrons, or ions.
Magnetic Energy - This form of energy results from a magnetic field.
Chemical Energy - Chemical energy is released or absorbed by chemical reactions. It is produced by breaking or forming chemical bonds between atoms and molecules.
Power is the rate at which work is done or energy is transferred in a unit of time. Power is increased if work is done faster or energy is transferred in less time.
Calculating Power
The equation for power is P = W/t
P stands for power (in watts)
W stands for the amount of work done (in Joules) or energy expended (in Joules)
t stands for the amount of time (in seconds)
In calculus terms, power is the derivative of work with respect to time. If work is done faster, power is higher. If work is done slower, power is smaller.
Since work is force times displacement (W=F*d), and velocity is displacement over time (v=d/t), power equals force times velocity: P = F*v. More power is seen when the system is both strong in force and fast in velocity.
Explanation:
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