Answer
The average force of air resistance was 6.4 N.
Work Step by Step
$a = \frac{v^2-v_0^2}{2y}$
$a = \frac{(27 ~m/s)^2 - 0}{(2)(55 ~m)}$
$a = 6.6~m/s^2$
Without air resistance, the acceleration would be $9.8 ~m/s^2$. The force of air resistance $F_f$ opposed the motion of the purse as it fell. So,
$F_g - F_f = ma$
$F_f = mg - ma$
$F_f = m(g-a)$
$F_f = (2.0 ~kg)(9.8 ~m/s^2 - 6.6 ~m/s^2)$
$F_f = 6.4 ~N$
The average force of air resistance was 6.4 N.
