When a raindrop falls in still air, its acceleration is given by g-0.5v, where g is ate acceleration due to gravity and v is the velocity. We then have a = dv/dt = g-0.5v.

a) Taking g as 10ms^-2, determine the velocity of the raindrop after two seconds if it starts falling from rest.

Ans: 12.64ms^-1

b) When the acceleration is less than 0.01mm s^-2, the raindrop will effectively be travelling at uniform velocity.

i) At what velocity does this situation arise?

Ans: 19.98ms/s

ii) How long does it take to reach this state?

Ans: 27.63s

Just need to know the working out, thanks.

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