Work, Energy, and Power
Energy can be defined as the capacity for doing work. moving with velocity of magnitude v, this energy can be calculated from the formula E= 1/2 mv^2. work power energy is a very important concept in physics. direction of movement, the work done is defined as a dot product of the force and the displacement. In physics, a force is said to do work if, when acting, there is a displacement of the point of Work transfers energy from one place to another, or one form to another. The time integral of this scalar equation yields work from the instantaneous power, and kinetic energy from the scalar product of velocity and acceleration.
If you drop an object it falls down, picking up speed along the way. This means there must be a net force on the object, doing work.
This force is the force of gravity, with a magnitude equal to mg, the weight of the object. The work done by the force of gravity is the force multiplied by the distance, so if the object drops a distance h, gravity does work on the object equal to the force multiplied by the height lost, which is: An object with potential energy has the potential to do work.
In the case of gravitational potential energy, the object has the potential to do work because of where it is, at a certain height above the ground, or at least above something. Spring potential energy Energy can also be stored in a stretched or compressed spring. An ideal spring is one in which the amount the spring stretches or compresses is proportional to the applied force.
This linear relationship between the force and the displacement is known as Hooke's law. For a spring this can be written: The larger k is, the stiffer the spring is and the harder the spring is to stretch.
If an object applies a force to a spring, the spring applies an equal and opposite force to the object. This is a restoring force, because when the spring is stretched, the force exerted by by the spring is opposite to the direction it is stretched. This accounts for the oscillating motion of a mass on a spring. If a mass hanging down from a spring is pulled down and let go, the spring exerts an upward force on the mass, moving it back to the equilibrium position, and then beyond.
This is summarized in the graphic below. Power Power is defined as the rate at which work is done upon an object. Like all rate quantities, power is a time-based quantity.
Power is related to how fast a job is done.
Mechanics: Work, Energy and Power
Two identical jobs or tasks can be done at different rates - one slowly or and one rapidly. The work is the same in each case since they are identical jobs but the power is different. The equation for power shows the importance of time: Special attention should be taken so as not to confuse the unit Watt, abbreviated W, with the quantity work, also abbreviated by the letter W. Combining the equations for power and work can lead to a second equation for power. A few of the problems in this set of problems will utilize this derived equation for power.
Mechanical, Kinetic and Potential Energies There are two forms of mechanical energy - potential energy and kinetic energy. Potential energy is the stored energy of position.
In this set of problems, we will be most concerned with the stored energy due to the vertical position of an object within Earth's gravitational field. Kinetic energy is defined as the energy possessed by an object due to its motion.
- Work, Power, and Energy
- Power (physics)
- Work, Energy, and Power
An object must be moving to possess kinetic energy. The amount of kinetic energy KE possessed by a moving object is dependent upon mass and speed. The total mechanical energy possessed by an object is the sum of its kinetic and potential energies.
Work-Energy Connection There is a relationship between work and total mechanical energy.
Work, Power, and Energy - Wikiversity
The short way is to combine the formulas, replacing F with mg and using h height in place of d: A mass is moving and can do work when it hits another object. Electrons can flow out of a battery or capacitor and do work on another electrical component such as a light bulb. Although massless, a photon does have energy; in the amount hf where f is the photon's frequency and h is Planck's constant. This is the energy that warms your face in the morning sun and burns your unguarded nose at the beach.
When some kinds of molecules are combined with others, energy can be released, usually as heat, light, or motion. When coal is burned it releases photon energy stored by plants millions of years before.
When hydrogen combines with oxygen to form water, heat is released as well.