Work, Energy & Power - Maths A-Level Revision
So, both Kinetic and Potential contribute to power. Another expression for power= force x velocity, as energy and workd are basically sane, and work =force x. The relationship between potential difference (or voltage) and electrical potential . Mechanical energy is the sum of the kinetic energy and potential energy of a . (a) What is the average power output of a heart defibrillator that dissipates . There are two main types of mechanical energy; potential and kinetic. Potential In both these cases the appropriate equation is Energy = Force * Distance.
Problem Set Overview This set of 32 problems targets your ability to use equations related to work and power, to calculate the kinetic, potential and total mechanical energy, and to use the work-energy relationship in order to determine the final speed, stopping distance or final height of an object.
The more difficult problems are color-coded as blue problems. Work Work results when a force acts upon an object to cause a displacement or a motion or, in some instances, to hinder a motion. Three variables are of importance in this definition - force, displacement, and the extent to which the force causes or hinders the displacement.
Each of these three variables find their way into the equation for work. The most complicated part of the work equation and work calculations is the meaning of the angle theta in the above equation. The angle is not just any stated angle in the problem; it is the angle between the F and the d vectors.
In solving work problems, one must always be aware of this definition - theta is the angle between the force and the displacement which it causes. If the force is in the same direction as the displacement, then the angle is 0 degrees.
If the force is in the opposite direction as the displacement, then the angle is degrees. If the force is up and the displacement is to the right, then the angle is 90 degrees. 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.
Work, Energy and Power
Power is related to how fast a job is done. 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. 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.
A typical example is the energy stored in a compressed spring, or the energy something has by virtue of being lifted a certain height above the ground.
Power and energy
In the case of the compressed spring, the force is the average "push" of the spring from its starting position to its compressed position, while the distance is the distance over which it is compressed. For gravitational potential energy, the force is the weight of the object, and the distance is the difference between its starting height and the height to which it is raised.
Kinetic energy is the energy a moving object has by virtue of its movement, and is equal to half the mass of the object times the square of its velocity. Thus if a ball is lifted to a certain height, it gains potential energy.
If it is then dropped, the potential energy is converted into kinetic energy as it looses height but gains speed. It then hits the ground and compresses like a spring.
Mechanics: Work, Energy and Power
The kinetic energy is converted back into potential energy in the form of elastic strain energy but with some loss in the form of heat - dead energy. The ball then expands again, and bounces up, thus converting the potential energy back into kinetic energy. And so on, until all the energy is lost into heat, and the ball stops bouncing.
Power Power is the rate of delivering energy, i.