# C4 Rate of changeWatch

#1
Q:
A hollow right circular cone is held vertex downwards beneath a tap leaking at the /s. Find the rate of rise of water level when depth is 6cm given that the height of the cone is 18cm and radius is 12cm.

My attempt:

volume of cone =

r =12
thus

volume of cone =
volume of cone =

cm/s

however the answer the book gives is \frac{1}{8\Pi } cm/s

0
4 weeks ago
#2
(Original post by bigmansouf)
Q:
A hollow right circular cone is held vertex downwards beneath a tap leaking at the /s. Find the rate of rise of water level when depth is 6cm given that the height of the cone is 18cm and radius is 12cm.

My attempt:

volume of cone =

r =12
thus

volume of cone =
volume of cone =

cm/s

however the answer the book gives is \frac{1}{8\Pi } cm/s

I think you need to get the basic rate of change of the cone right. You know that the "base" radius is 2/3 of the height and you're evaluating when h = 6. So write the volume of the water (not the total cone) in terms of "h", differentiate it and sub it into the expression for dh/dt.
0
#3
(Original post by mqb2766)
I think you need to get the basic rate of change of the cone right. You know that the "base" radius is 2/3 of the height and you're evaluating when h = 6. So write the volume of the water (not the total cone) in terms of "h", differentiate it and sub it into the expression for dh/dt.
thank you
0
X

new posts
Latest
My Feed

### Oops, nobody has postedin the last few hours.

Why not re-start the conversation?

see more

### See more of what you like onThe Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

### University open days

• Birkbeck, University of London
Thu, 21 Mar '19
• University of Wolverhampton
Thu, 21 Mar '19
• Edge Hill University
Fri, 22 Mar '19

### Poll

Join the discussion

#### Where do you need more help?

Which Uni should I go to? (68)
15.74%
How successful will I become if I take my planned subjects? (44)
10.19%
How happy will I be if I take this career? (81)
18.75%
How do I achieve my dream Uni placement? (61)
14.12%
What should I study to achieve my dream career? (46)
10.65%
How can I be the best version of myself? (132)
30.56%