Why is it easier to lift a heavy stone under water than in air?
551775
The water supplies lift force. Archimedes.
1051142
because water molecules are heavier than air molecules.  If you think about it, these heavy molecules are weighing down (even though they are suspended) on everything around them  with more force (which is proportional to the mass).
278046
Depends on what the "mass" is (its density)!  If the mass is more dense than water, then the mass is heavier - if the mass is less dense than water, then the mass is lighter than water.  Ice is the solid form of water and it is less dense, therefore it floats.
857981
Because alcohol is lighter than water.
427260
You DO have to consider bouyancy.  The person who said the force of the water can be neglected is incorrect.\n   The bouancy is equal to the weight of the water displaced.  Volume of the rock is 20/4200 = .004762m^3.  Water weighs 1 gm per cubic centimeter, or 1000 kg/m^3, weight of water displaced is therefore 4.762kg.  Subtract this from 20kg to get 15.238kg.  Multiply by 9.8m/s^2 = 149.3 Newtons
98234
The crust is way lighter than the rock of the lower mantle, and its volume is tiny in comparison. So if by "easily" you mean how much energy is required to move the rock, then the crust moves around much easier than the rock in the lower mantle.
484307
in air= 340m/s\nin water=1500m/s\nin solid=4500m/s
3535
well, (heh),\n\nlifting a mass m of anything a height h against the force of gravity requires an amount of energy that is equal to E = mgh, where g is the acceleration of gravity - 9.8 m/s^2.  \n\nthe power comes from dividing by how long it takes to do this - power is energy / time.  so P = mgh/t.  that means the pump requires that much power to do so.\n\nso, if you decrease h in the above equation, the power goes down.  it is a linear relationship, so if you halve the height over which you are pumping, you halve the amount of power required.\n\nnote that this ignores the frictional nature of water, which is reasonable if the water is not moving very fast in the pump or pipes.  if it is, you have a more complicated problem.
855462
ice has lower density, so it will either have larger volume or lower mass/weight than water.
742795
The water provides resistance.
1163482
1 ) It is easy to roll and move from place as it is too heavy to lift.\n\n2 ) The main reason is that it wont enter the man hole. If it is aquare it will enter the man hole easily.
386178
Below.\nWhy?\nBecause at 100ft above water you only feel the air pressure there. While at 100ft below water, you feel both the air pressure ( strictly spreaking in physics ) plus the water pressure there.\n\nAlso, note that water is more dense than air. This means for each space, water exerts more pressure compared to air for that same displacement of space.\n\nFurther, pressure that we feel is created due to the displacement of water or air moleculs respectively by the object. So, neighbouring air/water moleculs try to "displace out" the object that caused the "imbalance" where originally there were only air/water moleculs before the placement of the object.
42743
It is called the dead sea because there is not alot of life in it...however the good news is its hard to get things to sink there.  The reason for both of these thigns is the salt content of the water, things cant live if teh water is to salty.  The reason things float is because water is more dense when there are other minerals and compounds in it, thats why its easier to float in the ocean, just think of the dead sea as an ocean with lots more salt\n\nhope this helps!!
722824
water is denser than wood
825037
For the cork to sink it must raise the water level. Since it must raise the water against the force of the centrifuge - pushing harder on both just doesn't do the job (of sinking the cork).
888797
We weight the same, regardless of whether we're in water or not.  Buoyancy and density give us the feeling of weighing less in water.  You would get the same answer if you filled that tub with 150 lbs. of rocks.  Rock just happens to be a lot more dense than water, and not as buoyant as the human body :)\n\nVolckhart\nhttp://www.zeuslegacy.com/register.php?ref=2854
741308
that's why it's called 'leverage', because you're trading the weight of an object for the distance you need to move it - this equals less effort