Fluid Mechanics and Hydraulics Flashcards
7 cards from real Bennett Mechanical Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Fluid Mechanics and Hydraulics flashcards as text
An object floats in water when its weight is:
Answer: Equal to the buoyant force
An object floats in equilibrium when its weight equals the buoyant force pushing up.
Archimedes' principle states the buoyant force on a submerged object equals the weight of the:
Answer: Fluid displaced by the object
Buoyant force equals the weight of the fluid the object displaces.
Why does a steel ship float even though steel is denser than water?
Answer: The hull shape displaces enough water to equal the ship's weight
The hollow hull displaces a large volume of water whose weight supports the ship.
Two balls of equal size are submerged: one is solid steel, one is hollow plastic. The buoyant force on them is:
Answer: The same on both
Buoyant force depends on displaced volume, which is equal for same-size objects.
An object will sink in a fluid if its average density is:
Answer: Greater than the fluid's density
When an object is denser than the fluid, gravity exceeds buoyancy and it sinks.
A submarine descends by:
Answer: Increasing its overall density by filling ballast tanks with water
Flooding ballast tanks raises the sub's density above the water's, so it sinks.
An object weighs 50 lb in air but only 30 lb when submerged in water. The buoyant force on it is:
Answer: 20 lb
The apparent weight loss equals the buoyant force: 50 − 30 = 20 lb.