How do you work out the cost of electricity per cycle?

Question

I'm working on a physics analysis of The Giant Drop and one of the requirements is to figure out the cost of electricity per cycle. If electricity costs 14.8 cents per KWhr and one kwhr is 3600KJ, how do I figure out the cost per cycle? Do I just need the duration of the cycle?

Answer 1

What do you mean by cycle? do you mean one cycle of the 60Hz? or is it 50Hz?

In the US, one cycle is 16.6 ms

The problem is that kWhr is a unit of energy, not power. If I divide by 16ms, it becomes a power, and the cost does not change, as the cost is per unit of energy.

Bottom line: cost per cycle doesn't make sense, as the cost is per unit of energy, and does not involve time. In other words, cost per kWhr or J is the same, no matter what the time interval.

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Answer 2

It's interesting how words mean different things to different people!

By "cycle" could it mean once round the ride?

To work out the work done to get the car to the top of the drop?

Potential energy = mgh that sort of thing?

Answer 3

To start with you need the frequency of the AC.  In the States, that's f = 60 cycles per sec (aka Hertz).  It costs you 14.8 cents for a KW of energy over one hour.  The number of cycles in an hour is N = f*60*60 = 3600*60 cycles, where the 3600 is the number of seconds in an hour and the 60 is the number of cycles per second.  Divide c = C/N to get the cost per cycle where C = 14.8 cents per KW hr.  You can do the math.

This is a problem in units rather than a physics problem

Answer 4

You need to know the use per billing period and the amount of time in the billing period.

If the billing period is 30 days you use

30 days * 24 hr/day * 60 min/hr * 60 sec/min * 60 cycles/sec

The amount of electricity that you use during the billing period will be the dominating factor.

A person who uses 10 KWH per month will have a charge that is only 10% of a person who uses 100 KWH per month.

If you go through the mathematical gymnastics of converting months to cycles (Hz,) the first person will still only be paying 10% of the amount per cycle that the second person pays per cycle.