A cold yam is put into a hot oven, the temperature of the yam begins to rise. The rate R in degrees per minute at which the temperature rises is governed by Newton's Law of Heating, which says that the rate is proportional to the temperature different between the yam and the oven. If the oven is at 350 degrees and the temperature of the yarn H degrees F.

a) write a formula giving R as a function of H

i know that the proportion formula is y=kx. would i put the 350 in for y and leave x as the variable? i don't know what to do. thank you.

1 answer

The question tells you that the rate (R) is proportional to the temp difference (D) between the yam and the surroundings.

so R is proportional to D

or R=kD

if the temperature of the yam is H and the temperature of the surroundings is 350 then

D=350-H

so R=k(350-H)

which makes sense as the rate of heating will approach zero as H approaches 350.