What gas law is needed to solve the following problems. (i. e. Boyle, Charles, Avogadro, Ideal)

A hot air balloon expands to a volume of 3 x 108L at 68˚C, what is the temperature of the air in the balloon if the balloons volume contracts to a size of 2.75 x 10^7L?

2b2t

explanation:

2b2t

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.