Answer:
k = 40 N/m
Explanation:
A spring's energy is given:
[tex]U = 0.5kx^2[/tex]
U is the energy in the spring, k is the spring constant and x is the spring displacement.
We are told that the spring stores 5J of energy, therefore, U = 5J. We are also told that the spring is compressed by 0.5m, so the spring x = 0.5m
[tex]5 J = 0.5k(0.5m)^2\\5J = 0.5k(0.25m^2)\\5J = k*(0.125)m^2\\\\k = 5J/(0.125)m^2\\k = 40 N/m[/tex]
k = 40 N/m
Hope this helps!