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hardygirl989
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Homework Statement
A small piece of Styrofoam packing material is dropped from a height of 2.00 m above the ground. Until it reaches terminal speed, the magnitude of its acceleration is given by a = -g + bv. After falling 0.500 m, the Styrofoam effectively reaches terminal speed, and then takes 5.00 s more to reach the ground. (a) What is the value of the constant b? (b) What is the acceleration at t = 0? (c) What is the accleration when the speed is 0.150 m/s?
Homework Equations
ƩF=ma
W = weight
FD = resistant force
The Attempt at a Solution
I drew a free body diagram with the resistance force pointing up and the weight pointing down, where up is positive.
ƩF=W-FD=ma
-mg + bv = ma
-(1)g + bv = (1)a
-g + bv = a
bv-g = 0
b = g/v
I am stuck here because I am not sure how to find the terminal velocity. Do I do v=x/t=0.05/0.150=10/3≈3.33 m/s? That would make b = 9.8/(10/3)=2.94Kg/s, which seems too high...Can anyone help? Thanks.