In: Physics
1. For each part, select the best underlined option, then explain why it is the best. If you want to keep a hot beverage hot as long as possible, should you:
a. Store it in a bottle that is tall and thin, or one that is short and wide? (The short and wide one has a bigger surface area, but they both have the same volume)
b. Wrap the bottle with a one centimeter thick sheet of wool or a two centimeter thick sheet of wool?
c. Increase the temperature of the room the bottle is in, or decrease the temperature of the room the bottle is in?
Equations:
v = λ f (velocity = wavelength * frequency)
Rate of cooling = A ΔT (cooling rate = inverse of resistance * Area * Temperature difference)
as rate of cooling is givenn as = A ΔT so bigger the surface area bigger will be the rate of cooling or heat radiation so
a) in the 1st question short and wide has greater suraface so it will cool down fast and we want to keep the beverage hot as soon as possible so we will choose tall and thin.
b) wrapping the bottle with two centimeter thick woolen sheet increase its area which will turn out to be greater rate of cooling but if we thicken the woolen sheet the temperature of the surface will be very very much compare to the case of 1 cm thick woolen sheet and lower the surface tempertare will result in to very small radition of heat as temperture difference will be very small so we use two centimeter thick woolen sheet to keep it hot.
c) if we increase the temperature of the room the bottle is in the temperature difference reduces which results into decay in rate of cooling so beverage remains hot for longer period of time as compare to decrease the temperature of the room the bottle is in. as ΔT decreaces in 1st case.