Please solve with the formulas in the picture

Q-1) A spherical biscuit ( 5cm diameter) taken from the oven at 210C. Biscuit is kept under air flowing with velocity =1m/s. It is aimed to decrease the surface temperature of the biscuit to 30C before packaging. Air is 25C and at 1atm pressure. Weight of the biscuit is 40 grams. Cp of the biscuit is 2500 J/kgK. Heat loss due to radiation and conduction is negligible a) What is the average convection heat transfer coefficient? b) Calculate the cooling time of biscuit Q-2) A spherical biscuit ( 5cm diameter) taken from the oven at 210C. Biscuit is left in room until surface temperature drops to 30C. There is no air flow inside of the room. Air in the room is 25C and at 1atm pressure. Weight of the biscuit is 40 grams. Cp of the biscuit is 2500J/kgK. Heat loss due to radiation and conduction is negligible. a) What is the average convection heat transfer coefficient due to natural convection? b) Calculate the cooling time of biscuit 1. Natural Convection from Vertical Planes and Cylinders: - For an isothermal vertical surface or plate with height L less than 1m, the average natural convection heat transfer coefficient can be expressed by the following general equation; NNuu=khL=a(2L32gTkcp)m=a(NGrNPr2)m ELOW PAST SINGLE SPHERE: When a single sphere is being heated or cooled by a flu flowing past it, the following equation can be used to pred the average heat-transfer coefficient for a NRE= L.v. / of 1 70000 and a NPR of 0,6 to 400 ; NNu=2.0+0.60NRee0.5NPr1/3