The first step is to calculate the acceleration of the swimmer as she slows down and comes to rest. We would apply one of Newton's equation of motion which is expressed as
v^2 = u^2 + 2as
where
v = final velocity
u = initial velocity
a = acceleration
s = distance covered
From the information given,
u = 1.23
v = 0 because the swimmer came to rest
s = 2.2
By substituting these values into the equation,
0^2 = 1.23^2 + 2 x a x 2.2
0 = 1.5129 + 4.4a
4.4a = 0 - 1.5129 = - 1.5129
a = - 1.5129/4.4
a = - 0.345 m/s^2
The negative sign tells us that she was slowing down.
Recall,
net force = mass x acceleration
From the informtion given,
mass of swimmer = 52kg
Thus, the force exerted on her by the water = 52 x - 0.345
the force exerted on her by the water = - 17.94 N