Question

example of positive and negative terminal velocity

Answer 1

positive terminal velocity is when an object has attained its maximum velocity in the direction of motion..... negative terminal velocity is the velocity of the consecutive layers in the viscous medium which leads to the forward motion of the body

Answer 2

Hiii friends
When a spherical body falls through a viscous fluid, it experiences a viscous force. The magnitude of viscous force increases with the increase in velocity of the falling body under the action of its weight. As a result, the viscous force soon balances the driving force (weight of the body) and the body starts moving with a constant velocity known as its terminal velocity.
In case of upward motion of sphere, terminal velocity will be negative otherwise it is positive,
For example, in case of rising bubbles in a liquid, we see that the density of the bubble is less than the density of the enclosing liquid, so there will be an upward motion. This indicates negative terminal velocity as the downward direction is considered as positive.
If density of sphere is greater than the enclosing liquid, the terminal velocity will be positive.