A 67.0 kg person, standing on a diving board, dives straight down into the water. Just before striking the water, her speed is 5.50 m/s. At a time of 1.75 s after she enters the water, her speed is reduced to 1.10 m/s. What is the net average force (magnitude and direction) that acts on her when she is in the water?

Question

uuhh.. F=ma?

Answer 1

Kinematic description of decelerated motion of the diver gives
V=Vo-a•t
a = (Vo-V)/t = (5.5-1.1)/1.75 = 2.51 m/s^2.
From Newton’s 2 law
F = m•a = 67•2.51=168.5 N