Thread: please check DE problem

hi everybody, again i'm asking your's help as i have solved some DE problems, it seems to me that i've done all correct but as always my results don't match with those are given i the book.

1. water flows with the speed of 1,8 liters/sec in the box which has a form of parallelepiped with size 0,6 x 0,75 meters and height 0,8 meters. there is a hole in the bottom of the box with area 2,6 cm^2. calculate the time after which the box will be full.

2. a funnel has a form of cone with radius R=0,06 meters and height H=0,1 meters. it is set as its top looks down. calculate time in which all water will flow out of it, if it has a hole with diameter of 0,5 cm.

first one is weird but second one has answer of 28 seconds. i used g=10

In the first problem, I am worried you may have rounded too imprecisely, especially in the second line. Also, you want the time taken for the height to go from 0 to 0.8, so you can use a definite integral.

In the second problem, your description has a cone of radius 0.06m while the diagram has diameter 0.06m. Also, I'm not sure where the factor of 0.6 came from in the speed of water leaving the hole.

yes my bad, there is a mistake in the description, cone has dimeter 0,06m. and there is a formula written in book, telling that speed of water leaving the hole is as written with factor of 0,6