Everyone has noticed that when they are in the water they can lift their friends up without too much effort. It appears that when in water things do not weigh the same as they do out of water.
When asked if water changes the weight of steel I must say yes. Underwater steel weighs 12.7% less than it does out of the water.
How Much Does Steel Weigh Underwater?
A steel item that weighs 100 pounds would weigh about 87.3 pounds. That is a standard ratio of 12.7%. A steel item weighs 12.7% less in water than on land.
How Does Water Make Steel Lighter?
Water does not actually reduce the weight of the item. Water helps you to lift an item so the item is lighter.
Buoyancy is what makes the items underwater seem to be less heavy or dense. Buoyancy in water is an upward force of the liquid that supports some of the weight of the item and helps you to lift that item.
Considering Weight
The apparent difference in how much a steel item weighs when you are carrying underwater compared to when you carry it on land is a good way to determine weight association.
Other weight associations or considerations are broken into different categories.
Operational weight: the operational weight of an item is the measure of force that must be exerted in order to support the item in question.
If you consider operational weight then steel items in water weigh much less than steel items on land. The water helps to support the item so the amount of force you have to exert is lessened. Therefore, the weight is reduced.
Gravitational Weight: the gravitational weight of an item is measured by the force of gravity on the item.
If you consider gravitational weight then a steel item underwater weighs the same as a steel item on the beach because they have the same amount of gravitational force.
NASA uses gravitational weight in all of its calculations. Weight is represented by the equation F= m x a. (Force equals mass times acceleration) The formula you use to discern the gravitational weight of an item is F= m x 9.8 m/s2.
The gravitational weight of objects close to the earth is equal to the weight they will have while sitting on the earth’s surface.
Assistance by Water
Archimedes made the discovery that anything submerged in water has to displace a certain amount of water. The water that is displaced actually lifts the object up with a force that is equivalent to the weight of the item.
Water displacement and weight reduction of items in water is part of the Archimedes Principle. He made his discovery while bathing. He noticed as he got into his bath that the water level at the side of the tub rose. He also noticed that the more of his body that went into the water, adding more weight, the more the water rose.
To determine the amount of water an object will displace you have to pay attention to the mass or size of the object and the density of that object. A blow-up child’s ball made for playing in water can have the same mass (size around) as a soccer ball.
The two balls will, however, have different densities because they are made from different items. The soccer ball may be the same size around as the beach ball but it will have a weight that is far greater than that of the beach ball.
Because of the increased weight, the soccer ball will displace a greater amount of water when it is submerged. That means the soccer ball will feel significantly lighter when underwater and the beach ball will not seem to reduce by weight as much when it is submerged.
Test the Steel Weight
One thing you can do to determine the weight of steel underwater is to conduct your own experiment.
You Will Need
A tub of water deep enough to submerge the steel items you choose
2 steel items, like balls or pieces of steel that are almost identical in size and weight.
What To Do
Put one of the steel items in your right hand and one in your left hand.
Submerge one of the items.
Feel the weight difference of the item you are holding above the water and the one you are holding beneath the water surface.
Frequently Asked Questions
Does Steel Weigh Less Underwater?
Technically steel does weigh less underwater than on the ground.
Does Steel Weigh The Same Underwater?
No it does not. When steel is submerged it weighs less because of how the weight is determined. To determine underwater weight the volume of liquid displaced by the item is subtracted from the item weight to determine the underwater weight.
How Much Lighter is Steel Underwater?
A piece of steel that weighs about 32 pounds on land would be 19 pounds lighter in water. The 32-pound item would weigh about 13 pounds.
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