During which two minute time period is the temperature of the water changing fastest? Select one: a. 0-2 minutes b. 2-4 minutes c. 4-6 minutes d. 6-8 minutes Clear my choice

b. 2-4

Explanation:

Look at the slope of the line, between 0-2 and 4-6 the slope is only 10, but between 2-4 the slope is 20, so that's when the temperature is changing the fastest. In the same time it took for the water to increase by 20 degrees between 0-2 and 4-6, the temperature of the water increased by 40 degrees between 2-4 so that's when the change is the fastest.

answer: semi-infinite solid initially at a uniform temperature of 400 ◦c is cooled at its surface by convection. the cooling fluid at a constant temperature of 200 ◦c has a convective coefficient (ha) of 250 w/m2.k. the physical properties of the solid: k = 20 w/m.k and α = 4 * 10-5  m2/s. using δx = 0.04 m and δt = 10 s. write the finite difference equations describing the transient heat transfer of the first five δx and the temperature profile after 30 s.