When the drag force becomes equal to the weight of the body, the
| When the drag force becomes equal to the weight of the body, the acceleration ceases and the net external force acting in the body becomes
A. Zero and the body will move at constant speed
B. Light and the body will move forward
C. Zero and the body will move fast
D. High and the body will move at constant speed
Please scroll down to see the correct answer and solution guide.
Right Answer is: A
SOLUTION
Concept:
Drag Force:
- The component of resultant force in the direction of motion is called “Drag”. This component is denoted by ‘FD’. Drag force is the force exerted by the fluid in the direction of motion.
- Same amount of Drag force will be exerted by the body in the opposite direction of flow, if we consider the free body diagram of the body only.
From the above figure, (Considering only body forces)
If, Drag Force = Weight of Body
Then, Net external force acting on the body,
FE = FD – W = 0
∴ FD = W
According to newton’s second law, there is no acceleration if there is no force acting on the body.
We also know, acceleration is zero, when body is moving at constant velocity.
Hence, Option (1) is correct.
