Upthrust Flashcards

All 6 cards in this deck

What is upthrust?

The resultant upward force on an object in a fluid, caused by the pressure on its bottom surface being greater than on its top surface.

Why is the pressure on the bottom surface of a submerged object greater than on its top surface?

The bottom surface is at a greater depth, so there is a greater height of liquid above it.

What is the condition on the forces for an object to float in a fluid?

The upthrust equals the weight of the object (the forces balance).

What happens to an object whose weight is greater than the maximum upthrust the fluid can provide?

It sinks — there is a resultant downward force.

True or false? An object floats if its density is less than the density of the fluid it is placed in.

True. It can displace enough fluid to give an upthrust equal to its weight before it is fully submerged.

True or false? Upthrust acts only on objects that are totally submerged.

False. A partially submerged object also experiences upthrust.