Difference Between Work and Power
Main difference
The main difference between Work and Power is that Work is the total amount of energy required to move an object from one place by exerting an external force, and its SI unit is Joule, while Power is the rate of work and its SI unit is Watt.
work vs. Can
Work is the total amount of energy used to move an object from one place to another by applying an external force, for example: if a box of books is moved from the living room to the study room. However, power is the rate at which work is done; for example, if the book case moves slowly, it means less power is being applied and it will take more time. But if the container is moving quickly, it means more energy is needed to do the job quickly.
The System International (SI) unit of work is Joule (J). The symbol for work is denoted W while the SI unit of power is Watt (W), and the symbol for power is denoted P. Other larger units of work include a kilojoule = 1000 J = 10 J, 1 mega Joule = 1,000,000 J = 10 J and, electron volt (eV). While other larger power units boast 1 kilowatt = 1,000 W = 10³ W, 1 megawatt = 1,000,000 W = ^{106} W, 1 horsepower = 746 W and GW.
Work is the result of force (F) and displacement (S) in the direction of the force, so the equation can be written as (Work done = Force x displacement) or (W = FS) while Power is the fraction of work and time (work / time), so the equation is written as (Power = Work done / Time spent) or (P = W / t).
Comparison chart
Job | Can |
Work is known as the total amount of energy used to move an object from one place to another with external force. | Power is known as the amount of degree by which work is done. |
Symbol | |
The symbol for work is W. | Power is denoted by P. |
SI unit | |
The SI unit of work is Joules (J). | The SI unit of power is Watt (W). |
Equation | |
Work = force × Displacement. | Power = Work / Time |
Other Units | |
Electron Volt (eV), kWh, MWh, GWh | kW, MW, GW, horsepower (hp) |
relationship with energy | |
W = ΔKE | P = E / t |
SI base unit | |
Kgm² -² | Kgm² -³ |
What is work?
In the field of physics, work is the force necessary to move a body, and it is a scalar quantity with the equation W = F * S. If the applied force is constant, the work done will be equal to the scalar product of the external force applied to the body and the displacement that occurs due to that force. Examples from everyday life might be the gardener running the lawn mower around the garden and an ox pulling a plow in the field.
Some actions are not considered work; therefore, to do work, a force is always required on a body, causing its motion. A man pushes against the wall for isometric exercise, but the wall cannot move, so it does not count as work. According to physics, a ball thrown from the roof of the house hits the ground is considered work. In this phenomenon, gravity, as a force, acting on the ball, allows the ball to move downwards.
Joule (J) is the unit of work), it can be stated that the amount required to do work is one joule (1J) when a force of one newton (1N) is applied to the object to move it one meter (1m) in the direction of motion. the force, for example, 1 J = 1 N x 1 m. But it creates confusion with the unit of torque, which is also Nm, making it difficult to decide whether the unit is a measure of torque or a measure of work.
What is power?
In the field of physics, it is the rate at which work is done or the work that is done per unit of time. According to System International (SI), the unit of power is Watt (W) which is equal to Joule per second (1 Js -¹).
Its equation can be written as (Power = Work done / Time spent) or (P = W / t). The SI unit of power is Watt (W), which can be described as the amount of energy required is one watt (1W) to work at a rate of 1 joule per second (1 Js -¹).
To extract the working capacity of appliances such as an electric oven or generator, a light bulb, a water heater or a fan, an understanding of power is essential. Energy cannot indicate the working capacity of such devices because energy utilization always depends on time.
Because appliances are built to run at a fixed power, energy use changes (increases) over time, but power persists continuously. Therefore, energy utilization can be simply measured when the power is known. Also, the power capacity of power plants is indicated in larger units, for example, megawatts.
The energy can be of many types, such as electrical, mechanical and that of a rotating body; Electrical power can be expressed as p = I²R = VI = V² / R, where P = power, I = current, V = voltage. Mechanical power can be expressed as P = FV where F = force on object, V = speed of object.
Key differences
- Work is the amount of force required to move an object by applying external force, while power is the degree to which work is done.
- Joule (J) is the SI unit of work, while Watt (W) is the SI unit of power.
- Work is denoted by the formula W = FS; conversely, power is indicated by the formula P = W / t.
- The other units of work are kWh, MWh, GWh, Electron volt (eV), while other units of power are kW, MW, GW, horsepower (hp).
- The symbol for work is (W); on the other hand, the symbol of power is (P).
- The relationship between work and energy can be defined as the work done on a body is equal to the change in kinetic energy (KE). Whereas, the relationship between power and energy can be explained as the multiplication of power over time can give energy; similarly, dividing energy by time provides energy.
- The relationship between work and energy is expressed as W = ΔKE or, W = Ki − Kf where W = work done, K _{i} = initial kinetic energy, K _{f} = final kinetic energy, and ΔK = difference in kinetic energy; on the other hand, the relationship between power and energy is expressed as P = E / t.
- The SI base unit of work is denoted as Kgm²s -² conversely, Kgm²s -³ is the base unit of power.
Final Thought
The above discussion concludes that both work and power are terms of physics, but they differ in their characteristics, since work is the force applied to move n object and its SI unit is Joule, while power is the speed at which work is done and its SI unit is Watt. The work equation is expressed as Work = Force × Displacement, but the power equation as Power = Work / Time.