13. A jumper with a mass m = 80 kg, makes a long jump. Assuming that the force of air resistance is proportional to the speed, to determine how much longer Δt speed of the parachutist will be equal to 0.9 times the speed of steady motion. The drag coefficient k = 10 kg / s. The initial speed of a skydiver is zero.

Detailed solution. Decorated in Microsoft Word 2003. (Target decided to use formula editor)