Work Done and Power (GCSE Physics)
Work Done and Power
Power
Calculating Power
We can calculate a value for power using two different formulas. We previously looked at how to calculate power using work done. Here is a quick recap of what we learnt.
Work Done
Where:
- power, P, in watts, W
- time, t, in seconds, s
- work done, W, in joules, J
Question: A hair dryer does 45,000J of work in one minute. What is the power rating of the hairdryer?
- Write out the appropriate equation.
In this situation, the appropriate equation is:
Simply put the numbers into our equation.
Question: What is the power of a car engine that does 4500J of work in 1.5 minutes?
- Write out the appropriate equation.
In this situation, the appropriate equation is:
In the question, we have been given a value for time in minutes. The equation requires us to give the time in seconds, so we need to convert.
Now that we have the correct values, we can put the numbers into our equation.
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