Answer:
599 N/m
Explanation:
Let k (N/m) be the spring constant. According to the law of energy conservation, the total mechanical energy (kinetic and elastic) any any point along the spring must be the same:
[tex]kx^2/2 + mv^2/2 = constant[/tex]
[tex]k0.12^2/2 + 0.73*7.2^2/2 = k0.23^2/2 + 0.73*4.5^2/2[/tex]
[tex]0.0144k + 37.8432 = 0.0529k + 14.7825[/tex]
[tex]0.0385k = 23.0607[/tex]
[tex]k = 599 N/m[/tex]