# How much power physics question

1. Aug 5, 2014

### tennis38

For example, if it takes 60 watts of Power for a machine to fly, yet loses (for instance) 2.5 * 10^3 Joules of its energy because of the air resistance, whats the amount of "Power" that was really given in the first place?

2. Aug 5, 2014

### blintaro

I'm not sure I totally understand the problem but a watt is a joule/second, so if the plane needs 60 joules per second to maintain its velocity but loses 2500 joules per second because of air resistance, then the power required would be 2500 watts + 60 watts no?

3. Aug 5, 2014

### Simon Bridge

Since the power is energy per second - and you have only given a total energy figure for the amount lost to air resistance, then it is not possible to calculate the "real" power without also knowing the time of flight.

But I suspect you just need to reword the question to make it clear.

4. Aug 5, 2014

### tennis38

The time of flight is 30 minutes to reach a height of 2230 meters

5. Aug 5, 2014

6. Aug 5, 2014

### Simon Bridge

So if you lost 2500J in 30mins... How many J in 1sec?