Question

D'Alembert's Paradox states that the drag force on a body in an ideal fluid is

• A. Maximum
• B. Zero
• C. Infinite
• D. Equal to lift

Hint:

D'Alembert's Paradox states that \[ \boxed{ \text{An ideal (inviscid) fluid exerts zero drag on a body.} } \] In reality, viscosity produces boundary layers and flow separation, resulting in drag.

Answer 1

The Correct Option is B

Step 1: Recall D'Alembert's Paradox. D'Alembert's Paradox states that for an ideal fluid,
• the fluid is incompressible,
• the flow is steady,
• the fluid is inviscid (zero viscosity), and
• the flow is irrotational.

Step 2: State the consequence. Under these ideal conditions, the pressure distribution around the body is perfectly symmetric. Hence, the net drag force acting on the body becomes \[ \boxed{0.} \] Therefore, \[ \boxed{\text{Zero}} \] is the correct answer. Thus, \[ \boxed{(B)} \] is the correct answer.