Flow Past Immersed Bodies MCQ with answer and solution

Concept

Magnus Effect

Formula

F = S × (v × ω) or F_L = ρ × v × Γ

Step-by-step solution

1. Identify that the Magnus effect describes the motion of a spinning object moving through a fluid. 2. Recall that the rotation creates a velocity and pressure difference across opposite sides of the body, generating a sideways lift force. 3. Match this definition with the option for "Lift force on rotating bodies".

Explanation

The Magnus effect is the generation of a sideways force (lift) on a spinning object as it moves through a fluid, such as air or water. When a body rotates while moving, it creates a speed difference in the airflow on opposite sides, leading to a pressure difference that produces a net lift force perpendicular to the direction of motion.

Shortcut

A simple memory trick is: Magnus = Movien' Spin (or Magnus = Moving & Spinning) creates Lift. Alternatively, associate "Magnus = Major Lift on Spinning Objects" (like a curveball in baseball or a spinning soccer ball curving through the air).

Common mistake

A common mistake is selecting "Drag force only" by assuming the fluid force acting on a moving body in air is purely drag, ignoring the sideways lift force generated by rotation.