- #1

siwik39

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## Homework Statement

The terminal velocity of a 0.000038 kg raindrop is about 14 m/s.

(a) Assuming a drag force FD = -bv, determine the value of the constant b.

correct check mark kg/s

(b) Determine the time required for such a drop, starting from rest, to reach 63 percent of terminal velocity.

**2. The attempt at a solution**

I got part a by myself, where b= 0.0000266 kg/s

Part b has given me some trouble. I drew a diagram and set the the equation

F=ma=mg - (-bv) Then i tried solving for a, and using that to find t. However, I realized you can't use a=Vf-Vi/t because a is not constant. I have never done an equation like this with t and a non-constant a. I really don't want the answer because I won't learn anything, but any help or hints would be appreciated.