Answer:
[tex]U_k = 0.113[/tex]
Explanation:
using the law of the conservation of energy:
[tex]E_i -E_f=W_f[/tex]
[tex]\frac{1}{2}Kx^2=NU_kd[/tex]
where K is the spring constant, x is the spring compression, N is the normal force of the block, [tex]U_k[/tex] is the coefficiet of kinetic friction and d is the distance.
Also, by laws of newton, N is calculated by:
N = mg
N = 3.35 kg * 9.81 m/s
N = 32.8635
So, Replacing values on the first equation, we get:
[tex]\frac{1}{2}(138)(0.123)^2= (32.8635)U_k(0.281m)[/tex]
solving for [tex]U_k[/tex]:
[tex]U_k = 0.113[/tex]