The coefficient of kinetic friction for the rough horizontal surface is 0.66.
The given parameters;
Apply work-energy theorem; the work done the force of friction is equal to the energy stored in the spring.
[tex]F_kd_1 = \frac{1}{2} kd_2^2\\\\\mu_kmg cos(\theta)d_1 = \frac{1}{2} kd_2^2\\\\\mu_k(1 \times 9.8 \times cos(30)\times 4) = \frac{1}{2} \times 26.5 \times (1.3)^2\\\\33.95\mu_k = 22.39\\\\\mu_k = \frac{22.39}{33.95} \\\\\mu_k = 0.66[/tex]
Thus, the coefficient of kinetic friction for the rough horizontal surface is 0.66.
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