Energy & Power Flashcards

All 6 cards in this deck

What is power?

The energy transferred per second.

What is the unit of power, and what is 1 watt equal to?

The watt (W); $1\,\mathrm{W} = 1\,\mathrm{J/s}$ (one joule per second).

What is the equation linking power, energy transferred and time?

power (W) = energy transferred (J) ÷ time taken (s), $P = E / t$

What are the steps to calculate the power of a device from the energy it transfers?

e.g. $600\,\mathrm{J}$ transferred in $20\,\mathrm{s}$

1. Write $P = E / t$
2. Substitute with time in seconds: $P = 600 / 20$
3. Power $= 30\,\mathrm{W}$

How is $P = E/t$ rearranged to find the energy transferred?

$E = P \times t$ (energy = power × time in seconds).

True or false? A device with a power of $2000\,\mathrm{W}$ transfers $2000\,\mathrm{J}$ of energy each second.

True. A watt is a joule per second.