- #1
cleverfield
- 12
- 0
Homework Statement
The terminal velocity of a 3×10−5kg raindrop is about 5m/s . Assuming a drag force , and Drag Force = -bv
1. Assuming a drag force determine the value of the constant .
2. Assuming a drag force determine the time required for such a drop, starting from rest, to reach 63% of terminal velocity.
The Attempt at a Solution
I solved Q1 with an answer of b=6*10^-5 kg/s
for #2. I used Vfinal = Vinit + at
Equation 1 = V final = 0.63 of Vterm and therefore is 3.15 m/s
V init = 0
a = ?
Time = ?
for a I used the constant b and did FBD and N2
got Fdrag - mg = ma
Work:
-(6E-5kg/s)(3.15m/s) - (3E-5kg)(9.8m/s2) = (3E-5kg)a
but that gives a = -16.1 m/s2 which doesn't make sense to me. And i dropped that number in equation 1 above.
Thanks