Knowing more on Power

In physics, power is an important quantity that relates to Work and Energy. Physics defines work done as the product of an object’s displacement and external force applied. The capacity to get the work done is called energy. However, we need work done and time as the driving units to define power. There are many incidents in our day-to-day life where we encounter it. 

The article shares insights on what is power, and its other aspects. So, let us start with basic definitions and formulas. 

What is power?

In terms of physics, power is defined as the quantity of energy that gets converted or transferred per unit of time. In other words, we can define power as the amount of energy observed/unit of time. Power can also be described as the rate of work done/unit of time. And it is expressed as: 

P = dW/dt

Here, P represents power, W is the work done, and t represents time. 

Another formula for power: 

When a constant force is being applied across a certain distance, we can express work done as W = F.x 

where F is the force, and x is the distance. 

In this case, we can write power as P = dW/dt = d( F.x)/dt

= F * dx/dt

We know that dx/dt is velocity 

Putting the value, F*V. 

Here, V is the velocity. 

Hence, P = F*V 

One example is the power generated in pushing a stationary vehicle. The power is generated due to the product of the vehicle’s velocity and the wheel’s traction force.

Unit of power

In the international system of units, this is measured in terms of a watt (W). One watt denotes joule/second. Aside from this, traditionally, power is also measured in horsepower (hp). One unit of mechanical horsepower is denoted up to 745.7 watts. 

Some other units used for power measurement include: 

• erg/s
• dBm
• Calories/hour
• Foot-pounds/minute
• BTU/hour

Among all the above-mentioned units, Watt (J/sec) is the most widely accepted unit of power. 

How is varying power measured?

The rate of energy resources usage tends to vary over the course of time. For example, typically, we use minimal electricity usage in the early hours, which gets higher while cooking and during the evening due to the need for heating and lighting. Therefore, we need to know about various ways power is measured. 

Here are different types of power based on the ways they are measured: Instantaneous power, average power, peak power, and mechanical power. Let’s understand each of them.

What is Instantaneous power?

It is an amount of power that is calculated at a given instant of time. It is expressed using the formula P = V * I, where V represents the value of volts, and I represents instantaneous current. 

What is average power?

“What is average power” can be answered simply as the ratio of work done by the object to the time consumed by the object. The average power is expressed in the kiloWatt hour. 

It is denoted by: Pavg = dW/dt. 

What is Peak power? 

Peak power is defined as the highest value of instantaneous power that a particular system can acquire for a long haul. 

Or peak power is termed as the maximum power that a pulsing system can reach during a pulse. 

It is expressed as: 

Pp = Pavg/ DC

Here, Pp represents peak power

Pavg = average power

DC = Duty cycle

To find out the duty cycle

DC = PW / T

Here, PW represents pulse width, and T is time. 

A very typical example of peak power would be the stereo systems and car engines. However, the peak power obtained through these examples only lasts for a short time, to avoid any damage. 

What is mechanical power? 

In a mechanical system, power is known to be the combined effect of movement and forces. It is generally calculated as the product of an object’s force and velocity, or the product of a shaft’s applied torque and its angular velocity. 

Conclusion

There is a wide range of forms of work and energy that help in generating power in different ways. Power does imply that energy gets transferred via many incidents, converting itself into different forms. However, it’s impossible to convert from one energy form to another entirely without losing a portion of its part. All these actions are part of power generation. We hope you find the content we shared as well-informative and useful, helping you learn what is power and its types.