Answer:
[tex]490.5\ \text{N/m}[/tex]
Explanation:
m = Mass attached to spring = 14 kg
g = Acceleration due to gravity = [tex]9.81\ \text{m/s}^2[/tex]
x = Displacement of spring = [tex]78-50=28\ \text{cm}[/tex]
k = Spring constant
The force balance of the system is given by
[tex]kx=mg\\\Rightarrow k=\dfrac{mg}{x}\\\Rightarrow k=\dfrac{14\times 9.81}{0.28}\\\Rightarrow k=490.5\ \text{N/m}[/tex]
The spring constant for that spring is [tex]490.5\ \text{N/m}[/tex].