An athlete pulls handle a to the left with a constant force of p = 125 n. knowing that after the handle a has been pulled 30.25 cm its velocity is 3.2 m/s, determine the mass of the weight stack
b. (round the final value to two decimal places.)

Two equations are used for this problem: Newton's 2nd law of motion, and also an equation derived from the 2nd law specialized for linear motion at constant acceleration.

(1) F = ma
(2) 2ax = v2^2 - v1^2

We will use equation 2 first:

2a(0.3025 m) = (3.2m/s)^2 - 0^2
a = 16.926 m/s^2

Using equation 1:

F = ma
125 N = m(16.926 m/s^2)
m = 7.39kg