### Relation between power force and velocity in physics

Power may be defined as the rate of doing work or the rate of using energy. cases where a constant force moves an object at constant velocity, the power is. Work results when a force acts upon an object to cause a displacement (or a motion) or, There is a relationship between work and total mechanical energy. The quantity work has to do with a force causing a displacement. Work has nothing to do with the amount of time that this force acts to cause the displacement.

Mechanical, Kinetic and Potential Energies There are two forms of mechanical energy - potential energy and kinetic energy.

## Mechanics: Work, Energy and Power

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.

- How is power related to force and velocity?
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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. The final amount of total mechanical energy TMEf possessed by the system is equivalent to the initial amount of energy TMEi plus the work done by these non-conservative forces Wnc.

The mechanical energy possessed by a system is the sum of the kinetic energy and the potential energy. Positive work is done on a system when the force doing the work acts in the direction of the motion of the object. Negative work is done when the force doing the work opposes the motion of the object.

When a positive value for work is substituted into the work-energy equation above, the final amount of energy will be greater than the initial amount of energy; the system is said to have gained mechanical energy. When a negative value for work is substituted into the work-energy equation above, the final amount of energy will be less than the initial amount of energy; the system is said to have lost mechanical energy. There are occasions in which the only forces doing work are conservative forces sometimes referred to as internal forces.

Typically, such conservative forces include gravitational forces, elastic or spring forces, electrical forces and magnetic forces. When the only forces doing work are conservative forces, then the Wnc term in the equation above is zero. In such instances, the system is said to have conserved its mechanical energy.

## Power (physics)

The proper approach to work-energy problem involves carefully reading the problem description and substituting values from it into the work-energy equation listed above. Inferences about certain terms will have to be made based on a conceptual understanding of kinetic and potential energy.

For instance, if the object is initially on the ground, then it can be inferred that the PEi is 0 and that term can be canceled from the work-energy equation. In other instances, the height of the object is the same in the initial state as in the final state, so the PEi and the PEf terms are the same. As such, they can be mathematically canceled from each side of the equation. In other instances, the speed is constant during the motion, so the KEi and KEf terms are the same and can thus be mathematically canceled from each side of the equation.

Finally, there are instances in which the KE and or the PE terms are not stated; rather, the mass mspeed vand height h is given. In such instances, the KE and PE terms can be determined using their respective equations. Make it your habit from the beginning to simply start with the work and energy equation, to cancel terms which are zero or unchanging, to substitute values of energy and work into the equation and to solve for the stated unknown.

A car engine is an example of a machine that is given a power rating. The power rating relates to how rapidly the car can accelerate the car. If this were the case, then a car with four times the horsepower could do the same amount of work in one-fourth the time.

The point is that for the same amount of work, power and time are inversely proportional. The power equation suggests that a more powerful engine can do the same amount of work in less time. A person is also a machine that has a power rating. Some people are more power-full than others.

That is, some people are capable of doing the same amount of work in less time or more work in the same amount of time. A common physics lab involves quickly climbing a flight of stairs and using mass, height and time information to determine a student's personal power.

Despite the diagonal motion along the staircase, it is often assumed that the horizontal motion is constant and all the force from the steps is used to elevate the student upward at a constant speed.

Thus, the weight of the student is equal to the force that does the work on the student and the height of the staircase is the upward displacement. Suppose that Ben Pumpiniron elevates his kg body up the 2.

**Force, Work and Energy for Kids - #aumsum #kids #education #science #learn**

If this were the case, then we could calculate Ben's power rating. It can be assumed that Ben must apply an Newton downward force upon the stairs to elevate his body. By so doing, the stairs would push upward on Ben's body with just enough force to lift his body up the stairs. It can also be assumed that the angle between the force of the stairs on Ben and Ben's displacement is 0 degrees.

With these two approximations, Ben's power rating could be determined as shown below.

### Power (physics) - Wikipedia

Ben's power rating is Watts. He is quite a horse. This is shown below. This new equation for power reveals that a powerful machine is both strong big force and fast big velocity.