Upthrust on a body immersed in a fluid is equal to
- A. the weight of the body
- B. the weight of the fluid displaced by the body
- C. the volume of the body
- D. the density of the fluid
Explanation
This is Archimedes's principle, and the upthrust arises because pressure increases with depth, so the upward force on the bottom of the body exceeds the downward force on the top. A body floats when the upthrust at partial immersion already equals its weight. The principle also explains why a body appears lighter when weighed in water.