Help with an air resistance problem.

[john12933]

Part A)
A raindrop of mass 1.06 × 10−5 kg falls in air
and reaches a terminal speed of 4 m/s.
The acceleration of gravity is 9.8 m/s2 .
What is the value of the constant k that
determines the resistive force F = k v ?
Answer in units of kg/s

Part B)
If there were no air resistance, how long would
it take the raindrop to reach the same speed?
Answer in units of s.

I'm sorry there's no work, but I just have no idea where to start. We haven't even learned about air resistance in my class yet, and I was assigned this for homework.

 

[rock.freak667]

Part A)
A raindrop of mass 1.06 × 10−5 kg falls in air
and reaches a terminal speed of 4 m/s.
The acceleration of gravity is 9.8 m/s2 .
What is the value of the constant k that
determines the resistive force F = k v ?
Answer in units of kg/s.

Start by drawing a free-body diagram, what are the forces acting?

If the resultant force is downward, using the forces you listed, form an expression for the resultant force.