goodaskmansir 發問於 科學及數學數學 · 1 十年前

# (MAths) Choose the seted up equation

When a cold potato is put into a hot oven to bake, the temperature of the potato rises. The rate, Rt (in degrees per mins), at which the temp. of the potato rises is governed by Newton's Law of Heating, which says that the rate is proportional to the temp. difference between the potato and the oven. Set the oven = 350 degrees and the temperature of the potato = X degrees.

Which of the following can be used to model the temperature of the potato? (Select all that apply.)

a) R = kH+350 where k < 0

b) R = kH-350 where k > 0

c) R = k(H-350) where k > 0

R = k(350-H) where k > 0

R = k(H-350) where k < 0

### 1 個解答

• 1 十年前
最愛解答

R must be positive, i.e > 0

temperature change must be > 0

the heat coefficient k must be > 0

therefor R = k(350-H) where k > 0

2008-08-27 15:18:35 補充：

When H<350, heat change occurs so that R will be positive.

When H=350, no heat change on the potato will occur, so R = 0

2008-08-27 15:18:41 補充：

If H=350 and the potato has been taken out of the oven, the temperature change of the potato will be negative since the surrounding temp. is much lower than 350, said 30, then R=k(30-350) < 0. R become negative as the temperature of the potato is decreasing.