+0  
 
0
91
1
avatar

What's the formula for how long it takes to fill something up?

Also, can somebody point me in the right direction for the problem below? Please don't give me a solution, though.

 

During a rainstorm, an empty bucket moving up with vertical speed V gets filled in 2 minutes. The same bucket moving down with the same vertical speed V gets filled in 8 minutes. How long will it take to fill a motionless bucket?

 

I'm thinking five minutes but I'm not sure.

Guest Apr 3, 2018
 #1
avatar+26724 
+2

Let d = bucket volume per unit area

 

Let u be rain velocity (positive downwards)

 

Bucket going up:    d = 2(u + V).           (1)

Bucket going down:  d = 8(u - V).        (2)

 

Bucket stationary:  d = t(u + 0).             (3)

 

Eliminate V from (1) and (2) to get u in terms of d, then substitute u into (3) and rearrange to get t.

Alan  Apr 3, 2018
edited by Alan  Apr 3, 2018

16 Online Users

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.