After a parachutist jumps from an airplane (but before he pulls the rip cord to open his parachute), a downward speed of up to 180 km/h can be reached. When the parachute is finally opened, the drag force is increased by about a factor of 9, and this can create a large jolt on the jumper. Suppose this jumper falls at 180 km/h before opening his chute.
Determine the parachutist's acceleration when the chute is just opened, assuming his mass is 60 kg.