An engineer has just finished building a prototype of a lawn tractor that is powered by the sun. Which of the following should be the next step in the design process? A. Test the prototype and evaluate its performance.
B. Ask for the funding to build more copies of the prototype.
C. Build a second prototype that is different from the first.
D. Make changes to the prototype that will increase its performance.

i'm assuming that the correct answer is indeed the first one/ "a"..

you need to have a picture of the atom that way we can answer it

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.