If I weigh 85kg on land, how much will I weigh in fresh water and salt water?

Answer 1

Your mass will be the same but your weight, you are quite right in assuming, will be different. As a matter of fact, so long as you have air in your lungs, you will float in fresh water and float better in salt water, so your 'weight' will be negative in both fresh and salt water.

It is not actually possible to say how much you would weigh because it varies so much with your actual density, which is to do with the difference between the volume of water you displace and the volume of your body. Also, there are different degrees of saltiness - about the saltiest occurring naturally being the Dead Sea.

If you wanted to 'weigh' yourself in water, you would have to turn the scales upside down and measure exactly how much force it took to just submerge you - then count that as a negative value.

Answer 2

People using Kg (or pounds) as a unit of weight (I.E. a force) are just heading for confusion.
If you have a mass of 85 Kg then you will have this mass anywere, floating in space, falling in a lift, floating in water, bouncing on a trampoline it makes no difference.
A person with a mass of 85 Kg standing on the surface of the Earth will have a weight of just under 850 Newtons (F=ma). To avoid this force causing an acceleration and dropping you into the center of the planet there has to be an opposing force pushing up, this is normally applied by the soles of your feet or whatever is pressing against the ground. If floating in water then the force is applied uniformly over the submerged area but it is still 850 Newtons. If you are standing in water then some of this force will be exerted by your feet so you can get any number you like between 0 and 850 N. Most (OK almost all) scales are calibrated for an unspecified acceleration which is presumably about 9.81m/s/s but they are really measuring a force not a mass.

If you every hear someone talking about force in pounds or Kg then you should ask them what acceleration they are assuming. If they say gravity then you should ask them where. If they say on the earth then point out that it varies by 0.5% between the poles and the equator.

Peridot ( a few answers down ) the the right idea but has it backwards. Curly ( a few answers up ) gave the right answer.

Answer 3

To be Correct the kg is a measure of mass not weight. Look up the S.I. Units

Weight is the Force exerted by Gravity on the Mass.

Force = Mass x Acceleration i.e. F = mg where g is the acceleration due to the earth's gravitational attraction.

Force = Kg x 9.81 m/s^2 = Newtons

Depending upon where you are on the earth's surface, solid or liquid (at sea level) the actual value of g will vary. e.g. At the North or South pole you would weigh heavier than you would at the equator.

Given these constraints you will weigh the same irrespective of being on a solid or liquid support.

Do not confuse the Densities of salt and fresh water as having any bearing on your Weight.

The weight displaced in either medium will be constant. This means you will not displace as much salt water as you would fresh water. .

Answer 4

You will weigh less in fresh water and less again in salt water. Have you notice that you can kind of float in water, this is because you have air in your body, which is less dense than the water. If you stood on a weighing scales in water you would struggle to reach the same weight you did on dry land.
Since we are 2/3 water, our density is almost the same, so in salt water you would weigh even less since salt water would be more dense, due to the dissolved salt.
You would have the same mass though...

Answer 5

You would weigh the same, your weight is you mass combined with the gravitational force. Hence why you would weigh less on the moon, it has about 1/6 of the gravity of th earth.

You would show up as weighing less on a set of scales, only because you are more buoyant in salt water.

Answer 6

You never change weight (well, unless you put it on or lose some). You would only change mass if you went to another planet, where there is a different gravitational pull. Earth's gravitatioanl pull is 10, so if you weighed 60kg, your mass on Earth would be 60 x 10 = 600 N (Newtons).

Answer 7

you wouldn't weigh anything as weight is a measure of the pressure exerted on whatever you are standing on,,,,,,,,,your mass would still be 85kg, the same though as it would in space, on the moon, on the toilet or anywhere else you may venture

Answer 8

a slightly soggy 85kgs

Answer 9

The same

Answer 10

you should weight 85x.98 kg. and app same in salt water