We will define the Total mass to calculate the force, so our values are:
Total Mass 
The Weight is,
Through the hook's Law we calculate X.
, where x is the lenght of compression and K the Spring constant.
We don't have a K-Spring, but we can assume a random value (or simply let the equation in function of K)
I assume a value of 
Answer: William Thomson, better known as Lord Kelvin
We can solve for the acceleration by using a kinematic equation. First we should identify what we know so we can choose the correct equation.
We are given an original velocity of 24 m/s, a final velocity of 0 m/s, and a time of 6 s. We and looking for acceleration (a) in m/s^2.
The following equation has everything we need:
So plug in the known values and solve for a:
0 = 24 + 6a
-24 = 6a
a = -4 m/s^2
X + y = 5
x = 5 - y
2x - y = 7
2(5-y) - y = 7
10 - 2y - y = 7
10 - 3y = 7
10 - 7 = 3y
3 = 3y
y = 1
x + y = 5
x + 1 = 5
x = 5 - 1
x = 4
