Question 172833
his is from a worksheet.
An aquarium has a rectangular base that measures 100cm by 40cm and has a height of 50cm.  It is filled with water to a height of 40cm.  A brick with a rectangular base that measures 40cm by 20cm and a height of 10cm is placed in the aquarium.  By how many centimeters does the water rise? Thanks for any help!



Placing the brick in the aquarium will displace a volume of water equal to the brick. That volume will cause the level of the water to increase until that volume is reached.


The volume of the brick is 40 cm x 20 cm x 10 cm or 8000 cubic cm. That volume of water will be added to the tank which has a length of 100 cm and a width of 40 cm. So, the area of the tank's base is 4000 cm. If the water rises 1 cm, it would add a volume of water that was 100 cm x 40 cm x 1 cm or 4000 cubic cm. That isn't enough of a rise in water because we have 8000 cubic cm that the brick displaces. If the water rises 2 cm, it will have risen by a volume of 100 cm x 40 cm x 2 cm or 8000 cu cm and so the answer is 2 cm.