1. Oct 6, 2007

### physicsgirlie26

How many joules of energy does a 100-watt light bulb use per hour?
How fast would a 75 kg person have to run to have that amount of energy?

I found the energy of the light bulb to be 3.6×10^5 J but I have no idea how to find the second part. Can someone please help me? thanks.

Last edited: Oct 6, 2007
2. Oct 6, 2007

### neutrino

The second question is not very clear. "How fast would a 75 <what?> person..."? Is that supposed to be kilograms?

3. Oct 6, 2007

### physicsgirlie26

haha sorry! its supposed to be a 75kg person.

4. Oct 6, 2007

### neutrino

Okay. So, any object in motion possesses kinetic energy, right?

5. Oct 6, 2007

### physicsgirlie26

Yes. And K=1/2mv^2.

6. Oct 6, 2007

### neutrino

Right...can you solve the problem now?

7. Oct 6, 2007

### physicsgirlie26

so it would be 3.6×10^5 J=(1/2)75kg*v^2?

8. Oct 6, 2007

### physicsgirlie26

got it!
Thank you sooo much neutrino for pointing me in the right direction!! all i needed was a little help!

9. Oct 6, 2007

### neutrino

You're welcome. :)