Question

A body measures $5\,N$ in air and $2\,N$ when put in water. The buoyant force is:

• A. 7 N
• B. 9 N
• C. 3 N
• D. none of these

Answer 1

Answer: (C)

3 N

Answer 2

When a rigid object is submerged in a fluid (completely or partially), there exists an upward force on the object that is equal to the weight of the fluid displaced by the object. $\therefore$ Buoyant force $=$ actual weight $-$ weight in water $= 5N-2N$ $=3N$