Alright.. Having some trouble with the last question and math isnt my strong point so here it is.


Jeremy has a fish tank that has a 40 cm by 70cm rectangular base. the water is 2cm deep. When he drops a rock into the tank the water goes up 2cm. What is the volume in liters of the rocks?


Thanks in advance. Hopefully someone can help.

 

i think i got it... just gotta make sure..

 

Do the rocks float?

 

no, but it does displace water, hence making it rise
i had to do stuff like this when i was in training for well control, i forgot the formula though

 

The volume of the water + the rocks is twice as much as the water alone, therefore the volume of the rocks must be the same as the volume of the water. So all you have to do is calculate the volume of the water in the tank.

The calculation is simple: 40cm x 70cm x 2cm = 5600 cm^3

There are 1000 cm^3 in one litre, so the answer is 5.6 liters.

 

 

my bad.. its not 2cm. the water is 25cm deep.

 

Unless the water is too shallow to cover the rock, the depth of the water is irrelevant.

 

 

Um, mnemonic, perhaps?