Cups A and B are cone shaped and have heights of 32 cm and 14 cm and openings with radii of 15 cm and 12 cm, respectively. If cup B is full and its contents are poured into cup A, will cup A overflow? If not how high will cup A be filled?

3 Answers
Aug 24, 2016

height = 20.93cm

Explanation:

Volume cone = (pi r^2 h)/3

V_A = (pi xxcolor(red)(15^2xx32))/3 and V_B = (pixxcolor(blue)(12^2 xx14))/3

We only need to know which one is bigger, not the actual volumes.
We can therefore ignore pi and 3 as they are common to both.

By inspection we can see that :color(red)(V_A) >color(blue)(V_B)

So A will not overflow, but how high will the water reach?

The water in A and the whole cup A are similar figures.
Therefore we can compare the ratio of the cubes of the heights with the ratio of their volumes.

(h/H)^3 =V_B/V_A

(h/H)^3 = h^3/H^3 = h^3/32^3 = (color(blue)(12^2xx14))/(color(red)(15^2xx32)) = V_B/V_A

h^3 = (32^3xx12^2xx14)/(15^2xx32) = 9,1750.4

h = root3(9,1750.4) = 20.93cm

Dec 17, 2016

Cup A's height will be 7.68cm

Explanation:

Volume of cone=1/3pir^2h
A=1/3 pi^2*15^2*32
=1/3*3.141592654*225*32
=1/3*22619.467
=22619.467/3
Vol. A=7539.822cm^3
Vol.B=1/3pi12^2*12
=1/3*3.41592654*144*12
=1/3*5428.672105
=5428.672105/3
Vol.B=1809.557cm^3
New vol cup A=1/3*pi15^2*x=1809.557cm^3
235.619x=1809.557
x=1809.557/235.619
x=7.68cm

Dec 30, 2016

a. not overflow
b. height of cup A = 8.96cm

Explanation:

Volume of con = 1/3*pi*r^2*h.
where r = radius and h = height

Va=1/3*pi*15^2*32
Va = 2400pi

Vb=1/3*pi*12^2*14
Vb=672pi

so, cup A wont overflow because it is bigger than cup B.

let say T is the height of cup A when content in cup B poured to cup A.

Va = Vb

cancel(1/3)*cancelpi*15^2*T = cancel(1/3)*cancelpi*12^2*14 =(672*pi)

15^2*T = 12^2*14

T= (12^2*14)/(15^2)

T = 8.96 cm