Swhich could occur in a closed system?
a. chemical energy is transformed to electric
energy in the system.
b. during a transformation of chemical energy
to mechanical energy, thermal energy is
released to the environment.
c. electric energy from the environment is
transferred to the system.
d. radiant energy is transferred to the
environment.

diaria maybe go see a doctor about that

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.