E = P * t


P = E / t


E=energy (joules)

P = power (watts)

t = time (seconds)



Mass and weight

Uniform movement

Accelerated movement

Work / energy

Kinetic energy





Pressure and force

Elastic force (Hooke's Law)

Projectile motion



Power in mechanics

Power has already been defined in the context of electrical energy.

The more powerful something is, the faster it can perform work!

In the context of mechanics it means the same thing, obviously. But let's have some examples in mechanics:


1) A motor is capable of lifting a 50kg object , to a height of 100 m, in 1 min.

What is the power of this engine?

Let's first calculate the work done:

W = 50*10*100 = 50000 J

P = 50000 J / 60 s = 833.3 W

2) Motor B has twice the power. How long would take for it to do this same amount of work?

2*833.3 = 50000/t

t = 30 s





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