9. A scale is adjusted so that when a large, shallow pan is placed on it, it rea

Question

9. A scale is adjusted so that when a large, shallow pan is placed on it, it reads zero. A source of water at height h-2.5m above is turned on and water falls into the pan at a rate R=0.14kg/s. Determine (a) a formula for the scale reading as a function of time t and (b) the reading for 9s. (c) Repeat (a) and (b), replacing the shallow pan with a tal, narrow cylindrical container of area A -20cm2. Hint: While for the shallow pan, you may neglect the change in the water height, for the cylinder, you need to consider the rise in the water level. th ater height, for the cy

Explanation / Answer

You're looking for the changing mass in terms of the rate, R, time, t, and height, h. From what I can tell, you will not be able to express it in all 3 of those terms, only 2 of them (either R and t or R and h). Essentially, though, this will be as simple as m = R*t, but I believe you need to account for the distance the water is falling.

h = 1/2*g*t^2

So then the time is given by

t = sqrt{ 2*h/g}

Putting this into the rate equation above

m = R*t

b)

For t = 9s,

Reading is:

m = (0.14kg/s)*(9s)

= 1.26kg

Related Questions

Navigate

• Browse (All)
• Browse 9
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.