Why are Watt Hours not Watts per Hour? Are they the same thing?

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Why are Watt Hours not Watts per Hour? Are they the same thing?

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Anonymous 0 Comments

No, watts per hour and watt hours are not the same thing. Watts per hour would be W/h and watt hours is W*h.

Top explain what both mean, I’ll first explain what both components mean:

Hours are a measure of time (not so hard I guess)

A Watt is a measure of power. It says something about the rate at which energy is transferred.

A Wh (watt hour) is energy (just like calories and joules). Energy is the ability to change things. Like heating up stuff or move an object.

Here is an example to show this.

Heating up a pot of water takes energy. You transfer energie from a heatsource into the water. It takes a 1000 calories (or 1.16222222 watt hours) to heat up 1 kilogram of water with 1 Kelvin. This transfer of doesn’t happen instantaneously, it takes time. If it takes 1 hour to change the temperature of this pot of water, then the power with which this water is heated would be 1.16/1= 1.16 watt. If you want to do it faster, you need to increase the power.

So energy is power applied for some time (Wh=W x h, or in your school textbook: E=P x t) and consequently; power is energy over time (Wh/h=W or in your school books it would be P=E/t)

So what would W/h be?
This would mean that power would change over time in a linear way. To stay with the same example as above. If you would gradually turn the knob of the stove to get the water to heat up faster than you would change the power over time which is weird to do in a linear fashion.

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