As a raindrop falls from a cloud to the surface of Earth,
A.
its speed increases due to gravity.
B.
its speed increases due to air resistance.
C.
it moves at a constant speed.
D. it moves at a constant velocity.
The correct answer is A. Its speed increases due to gravity.
When a raindrop falls from a cloud to the surface of the Earth, it is subjected to the force of gravity. Initially, it starts falling from a state of rest, so its speed is zero. However, as gravity pulls it towards the ground, the raindrop accelerates and gains speed. This increase in speed continues until the raindrop reaches its terminal velocity.
Terminal velocity is the maximum velocity a falling object can achieve when the force of gravity is balanced by the force of air resistance. At terminal velocity, the raindrop stops accelerating and moves at a constant speed. However, it should be noted that terminal velocity is not reached immediately after the raindrop starts falling. Initially, the raindrop accelerates due to gravity, and as it gains speed, air resistance also starts to act on it. The raindrop continues to accelerate until it reaches a point where the force of air resistance is equal to the force of gravity. At this point, the raindrop's speed stabilizes, and it falls at a constant speed, which is its terminal velocity.
To summarize, as a raindrop falls from a cloud to the surface of the Earth, its speed increases due to the force of gravity. However, once it reaches its terminal velocity, it moves at a constant speed.