Formula: m(dv/dt)=-mg-kv.

Examples 1. A mass of 20 g is dropped from an airplane flying horizontally. Air resistance =kv, and k, the constant of proportionality is 10g/s. Considering only vertical motion:

1. Find the velocity as a function of time.
2. Find the velocity after 10sec, assuming that the body has not hit the ground.
3. If the gravitational force is assumed constant, what is the limiting velocity?