Calculating Energy Usage for a 100-Watt Light Bulb and Human Running Speed

[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?
Express your answer using two significant figures.



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.

 

[neutrino]

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

 

[physicsgirlie26]

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

 

[neutrino]

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

 

[physicsgirlie26]

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

 

[neutrino]

Right...can you solve the problem now?

 

[physicsgirlie26]

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

 

[physicsgirlie26]

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

 

[neutrino]

You're welcome. :)