if a 9.8 object is above a glass held up by a spring lift then why does it weigh 7.8 when in the water?
823590
Bouyancy. The 9.8 (you did not specify the units) object, when in water, is partially supported by the bouyant force. The bouyancy force is the weight of the displaced water. The water level is higher because the displaced water had nowhere else to go but up. The volume of water is still the same though.
182931
Lift under a liquid (or BOUYANCY FORCE) is defined as the weight of the volume of liquid displaced.  In other words, say a ball displaces 1 cubic meter of water.  The ball will be pushed back up with the same amount of force as the weight of that 1 cubic meter of water.\n\nSince water's density is 999 kg/cubic meter, we're looking at 999 kg of water (water is really heavy!).\n\nNow if we want the force of that water, we'd simply multiply it by the gravitational acceleration, 9.8 m/s/s:\n\n999 * 9.8m/s/s = 9790 Newtons (1 Newton = 1 (kg * m)/(s^2))\n\nSo the ball would be pushed back up with a force of 9790 Newtons.\n\nNow, the hard shell ball will (theoretically) not deform when subjected to the pressure of 10 feet of water.  So the *bouyance force* placed on the hard shell ball is easy to calculate, given the formula above.\n\nThe latex balloon, however, will shrink as it is exposed to increasing pressure, so the volume of water it displaces will be smaller. (I will not solve that problem here as it takes up quite a bit of space to show how much a balloon shrinks as it is subjected to increasing pressure.  Essentially it comes down to writing a spherical force balance and integrating over volume)\n\nConsequently, the bouyancy force exerted on the latex balloon will be smaller, and the ping pong ball would be forced back up through the water harder (and faster) than the balloon.\n\nAs an extreme, ever wondered what happens to helium filled balloons when they are released into the air and they float up until you can't see them anymore?  Since the atmospheric pressure is lower and lower the higher you go, the balloon expands until eventually it pops.  At that point, the popped balloon either falls back to earth or gets swept up into atmospheric currents, which can take it basically anywhere on earth.
613715
First find the volume of the object, i.e metal, by placing it in water and then u know the amount of water displaced.\nIf it displaces half the water than it's weight, then u know that it's specific gravity is twice that of water.
943048
Whenever the mass of an object is less than the mass of the liquid it displaces, it will float.  That's why a hunk of steel won't float, but a ship made of steel, enclosing lots of unoccupied space, will float.\n\nAs for the ice cream, its made up of lots of fat molecules whipped into a semi-solid.  Its mass is less than the mass of the root beer it displaces...therefore it floats
722868
B) FALL. The reason is that while the stone is in the boat (or otherwise floating or being supported by a floating object), it is displacing water equal to its WEIGHT, but when fully immersed, it displaces water equal to its VOLUME. This is less water (since if a volume of water equal to the volume of the stone weighed as much or more than the stone, then the stone's density would be less than that of water, which it isn't), and therefore the total water level in the lake will go DOWN.\n\nTo the other answerers: shame on you for not thinking through the problem carefully enough.
1151440
A net Force will cause a mass to acclerate.\nnet Force = mass * acceleration\n\nIn this case, you have two forces acting on the object, the force of 20 Newtons acting upward and the force of weight caused by gravity acting downward.\n\nIf the object has a mass of 600 grams (.6 kg), then the object has a weight of about 5.95 Newtons.  This force is directed downward (in what we will call the negative direction).\n\nThe net force is the sum of the two force acting on the object.\nnet Force = +20 newtons - 5.95 Newtons\nnet Force = 14.05 Newtons in the positive direction\n\nThis constant net force will cause a constant acceleration of the object in the upward direction,\nF = ma\n(14.05 N) = (.6 kg) * a\na = 23.42 m/s^2\n\nFrom here, there are actually any number of ways to solve this problem, but I am guess the one which you will be most familiar with will be to use the kinematic equation,\nd = v*t + 1/2 at^2\nwhere v is the initial velocity, t is the time, and a is the constant acceleration.\nIf this object experiences this net force (cause an acceleration) for a distance of 1.8 metes, this is the value we will plut into the equation for the distance (d).  We assume the object started from rest (v = 0).\n\n(1.8 m) = 1/2 (23.42 m/s^2) * t^2\nnow we simply solve for the time, t,\nt = sqrt (2 * (1.8 m) / (23.42 m/s^2))\nt = .392 seconds\n\nUsing this formula,\nv = a*t\nwhere v is now the objects velocity after experiencing a constant acceleration for time t, we solve for the object's velocitu when releases,\nv = (23.42 m/s^2) * (.392 s)\nv = 9.18 m/s in the upward direction.
913425
When the ice was floating on water, the water had lifted by certain level..tht level was equal to the weight of the ice..s when the ice melts , the water level wont increase since the water from icemelt is equal to the earlier weight of the ice ...and the water on which ice was floating had already risen to accomadate tht weight..so it wont rise again when the ice melts...
523637
I assume you meant to say, "taken under" water.\n\nWeight is the force which is exerted by gravity on an object.  No matter where the object is, under the same gravitational field, the object's weight is the same.\n\nAbove water, under water, beside water, the Lead and the concrete will have the same weight...all else being constant.\n\nWhat you are refering to is the effects of boyancy upon the appearent weight of the object.\nIn air, the effects of boyancy are usually negligible, but underwater, they play more of a role.\n\nWhen something is under water, it displaces its volume of water and by doing so, the water exerts a force back onto the object equal to its own weight.  The boyant force (weight of the displaced water) depends on the volume of the object, not its mass (as opposed to an object's weight which depends on its mass and not volume).\nSince the lead is much more dense than the concrete, despite having an eqaul mass, it displacing less water and have a smaller boyancy force acting upward on it.  This lower boyancy force means that the Lead would "feel" heavier than the water when the total net downward force is measured.
92955
The mass of an object is NOT the same as the weight. \n\nWeigh the object. In the avoirdupois system the weight is in pounds. In the metric system, the weight is in newtons. \n\nDivide the weight by the local acceleration of gravity (roughly 9.8 m/sec^2 for the metric system, and 32 ft/sec^2 for the avoirdupois system). The result is the mass of the system. In the metric system, the unit of mass is the kilogram. In the avoirdupois system, the unit of mass is the slug. \n\nThe local acceleration can vary from location to location on the earth, so one way to estimate the local acceleration is by using an object of known mass. Weigh the known mass, and divide its weight by the known mass to find an estimate of the local acceleration. \n\nThere are many other methods for finding the mass including multiplying the volume of the object by its density. The volume can be found by measuring it, or submerging the object in water (or other liquid) and measuring the amount of displaced water (or liquid).\n\nGravitational mass is the same as inertial mass, for unknown reasons, so one could also devise methods that estimate inertial mass. For example, one could measure the centrifugal force on a string attached to the object while it is being spun (by introducing a spring in between, and measuring the stretch of the spring, for example). One could stage an elastic impact between the object and another object of known mass, and knowing the velocities before and after impact, compute the mass of the object. \n\nThere are many many other methods one could use.
187607
The density of water is about 100 times the density of any gas .\nSo the gas will be lifted. (Archimedes law).\nBasicly the gravity energy decreases.
879947
Hello,\nDensity is mass per unit volume.  The density of fresh water is one gram of mass per cubic centimeter.  Since, the ocean water has salt in it, there is more mass per cubic centimeter of salt water.  If you think about a glass full of fresh water and a glass full of salt water, you can easily see that the glass full of salt water has a lot more material(mass) per cubic centimeter than the fresh water does.  So the glass full of salt water (or the ocean)is more dense than the glass full of fresh water.\nAnd that affects a boat by making it float higher.  When an object is placed in water, it displaces as much mass of water as is contained in the object.  Again you can think of a glass of water.  If the glass is filled to the top and you place an object of mass M-grams in the glass, then the amount of water that spills out is M-grams.  The object displaces the mass of the water by sinking into the glass.  Once it has displaced M-grams of mass, it can't displace any more, therefore it will stop sinking as soon as it displaces M-grams.  So since each cubic centimeter of salt water is made up of more mass than fresh water, the object will displace less cubic centimeters of salt water than of fresh water, so it will float higher.
668137
According to Archimedes Principle, the upthrust force on a body totally or partially immersed in a fluid is equal to the weight of the fluid displaced by the body. \n\nImagine a ship that has a weight of 2,000,000 N.  A large crane is lowering it into the water.  When a part of the keel is submerged, it displaces, say 500,000 N of water.  There is still a net downwards force of 1,500,000 N.  If lowered further, more water is displaced, and therefore the upward force increases, while the net downward force decreases.  There comes a time when the ship, as it continues to be lowered, has displaced 2,000,000 N of water.  What then?  The upward force just balances the weight of the ship, and it sinks on further into the water.\n\nIncidentally, a needle does not always sink in water.  Smear it with oil and gently lower it in a bowl of water.  It floats!!!  Of course, this has nothing to do with Archimedes Principle but rather with the surface tension of the water molecules.
289324
simple F=m*a\nm=0.8\na= the acceleration due to gravity (9.8 ms^2)\nWeight is 7.84 N\nthe conversion should be in your textbook from newtons to lbs and from lbs to oz
676069
it holds no water,its lighter than water so in short it floats they use it in flotation device ,because of durability and its light weight,the formula is for every  10 lbs 3 square inches so to float 300 lbs human your look at 90 in volume which can be 15 in tall by15 in round put on the bottom he be torpedoed up in seconds
291004
if an object is floating, the buoyant force on it equals its weight -- the vertical forces have to sum to zero.  try drawing a free body diagram to convince yourself of this.
379322
Your answer's wrong.  Water has weight too.\n\n... What does this have to do with computers?
208900
Specific gravity.\n\nPure water has a density of 1 (the mass of 1 cubic centimetre of pure water is precisely 1 gramme), if something was twice as heavy as water (i.e. it has twice the mass) it would have a specific gravity of 2, 6 times as heavy and the SG would be 6.  If something was half as light as water it's SG would be 0.5 and so on.