Which one of the following is an example of bodies where both dra
A. Hydrofiles
B. A tall chimney exposed to wind
C. Flow of water past a bridge pier
D. Motion of aeroplanes, submarines, torpedoes
Please scroll down to see the correct answer and solution guide.
Right Answer is: D
SOLUTION
Concept:
Forces on submerged bodies:
When a fluid flowing over a stationary body, a force is exerted by the fluid on the body. Similarly, when body is moving in a stationary fluid, a force is exerted by the fluid on the body.
The total force exerted by the fluid on the body is perpendicular to the surface of the body. Thus total force is inclined to the direction of motion. This total force can be resolved into two components, one in direction of motion and other perpendicular to direction of motion.
Drag Force: The component of total force in direction of motion is called “Drag”. Thus drag is the force exerted by the fluid in direction of motion.
Lift Force: the component of total force in direction perpendicular to motion is called “Lift”. Thus lift force is the force exerted by the fluid in direction perpendicular to the motion.
|
Object |
Type of Force |
|
Lift Force Only |
|
Drag force due to wind only |
|
Drag force only |
|
Lift and drag both forces |