Which of these is an example of dynamic equilibrium?
AA book lying on a table
BA ladder leaning against a wall
CA bridge supporting a static load
DA raindrop falling at terminal velocity
Answer & Solution
Correct answer: D. A raindrop falling at terminal velocity
1. Dynamic equilibrium means net force is zero but the body keeps moving with constant velocity.
2. At terminal velocity, gravity is balanced by air drag, so net force is zero.
3. The raindrop continues to fall at constant speed.
4. The other three are static cases of bodies at rest.
_Source: Selina Concise Physics ICSE Class 10, Ch 1 'Force' (icsehelp.com chapter extract)_
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