Ap Physics
posted by George .
On a clear day at the equator with the sun directly overhead, how long would it take to warm 10 kg of water 15 Co if the emissivity of the 1.0 m 2 surface is 1?
can someone help me work this out?

The solar flux from straight above on a clear day is about 1100 W/m^2. Your 1 sq meter area will receive 1100 W.
To raise the temperature 15 degrees C, the irradiating time T must satisfy
M*C*(delta T) = 1100 W * T
C = 4128 J/(kg*deg C)
delta T = 15 C
M = 10 kg
T = 563 s = about 9.4 hours
Solve for T