Hi, I have a question about buoyancy and water displacement. I have tried to figure this out for over an hour, but I have figured out nothing yet.
The density of water is 1.0 g/cm3. How many kilograms of water does a submerged 120-cm3 block displace? One kilgram weighs 9.0N. What is the buyant force on the block?
* The 3 next to cm is to the power of 3.
2006-09-11 09:50:13 · 3 answers · asked by k1ng_koopa713 3 in Science & Mathematics ➔ Physics
If the problem states that the 120 cm^3 block is "submerged," that means that it has been completely covered. As a result, it displaces its entire volume in water. Since each cm^3 of water has a mass of 1 g, 120 cm^3 of water has a mass of 120 g, or .12 kg. The force is equal to the weight of the displaced water. The problem states that one kg is 9.0 N, which is different from the usual value of 9.8 N. Using the given value, .12 kg of water weigs 1.08 N.
2006-09-11 10:06:00 · answer #1 · answered by DavidK93 7 · 2⤊ 0⤋
Not enough information, actually -- what is the block made of? The density of the object matters, because according to Archimedes, an object will sink until it displaces its own weight in water (weight being a property of a mass), up to the actual volume of the object itself. So a 120 cm3 block of lead and a 120 cm3 block of balsa wood would have the exact same measurements, but the first would sink and the other would float after displacing only a few cm3 of water, because it's so light. The lead couldn't float because it displaces 120 cm3 of water very quickly, but because it is denser than the water, it would have to displace a lot more. You could still get lead to float if you were able to form it into a hollow container that was wide enough that it DID displace more water. This is how a 90,000 ton aircraft carrier is able to float on water -- even though it is massively heavy, it's also simply big enough that it displaces 90,000 tons of water and still be above water.
So find out the density of your block, determine it's mass by multiplying the density by 120 cm3 and see if that number is larger than the 120g of water that it would displace.
2006-09-11 17:00:33 · answer #2 · answered by theyuks 4 · 0⤊ 0⤋
120 grams
120/1000*9=1.08 Newtons
2006-09-11 18:24:43 · answer #3 · answered by bruinfan 7 · 0⤊ 0⤋