F= -b*v

From Newton's Law:

F= m dv/dt =-b*v

Then, dv/dt=-(b/m)*v

If the velocity V(t=0)=V0

Then the solution for the above differential equation is

V(t)=V0*e

The velocity will not reach zero from mathematic point of view.

But it's magnitude will reduce to nearly 2% of its original value by the same time step t=4*(m/b) seconds.

if m/b=1s, V0=100m/s, (the following values are estimated values, use exponential function to calculate it's exact value.)

at t=4s, V0=100*0.02=2m/s,

at t=8s, v0=2*0.02=0.04m/s,

at t=8s, v0=0.04*0.02=0.0008m/s

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