Year 12s: what will be the first way you research your future options? >>

heat transfer rate

A roof measures 20 m by 50 m and is blackened. If the temperature of the sun’s surface is 6000 K, the radius of the sun is 7.5x10^8 m and the distance of the sun from the earth is 1.5x10^8 km, calculate how much solar energy is incident on the roof per minute, assuming that half is lost in passing through the earth’s atmosphere. Assume the roof is normal to the sun’s rays.

I will be glad if you can help me about this question. I dont know where to start solving it.Thanks for your help.

#john

Reply 1

AliciaJ703

I believe that this question is addressing a physics concept of power. There is a conversion you need to do plus some basic concepts you need to understand about the energy of the system and its surroundings. Since the question is asking about solar energy per minute then instead of addressing solely work, your problem becomes a power question. Power (P) is the rate of energy transfer which the unit for power is watt (equivalent to J/s). Power= ∆E/t where t is the time during which energy is transferred and ∆E is the energy change of the system which equals work W plus heat q. I don't remember the series of steps but maybe this will put you in the right direction I hope. Been a while since I have had physics.

Reply 2

AliciaJ703

If you're able to find the answer, please tell me.

Reply 3

AliciaJ703

Also, I would recommend that you duplicate this thread in the Medicine forum since there has to be students who have a background in physics.

Reply 4

Antzlck

This is a radiation problem. I don't know how much you know. Are you an engineering uni student?

You need to use the Stefan-Boltzmann law with a black body approximation.