eqn = {
    m == 54.7/1000,
    g == 9.8,

    m*g == (3^0.5)*f1+(6^0.5)*n1,

    ((2/3)^0.5)*f1+(-1/(3^0.5))*n1+2*((3^0.5)*c2/2+s2/(6^0.5))*f2+(-1/(3^0.5))*n2 == 0,
    -m*g+(-(2/3)^0.5)*f1+(-1/(3^0.5))*n1+2*(s2/(3^0.5))*f2+((2/3)^0.5)*n2 ==0,
    f1+2*f2*(-c2/(2^0.5)-s2/3-s2/6) == 0,

    2*f2*(-(3^0.5)*c2/2+s2/(6^0.5))+2*n2*(-(3^0.5)/6)+f3 == 0,
    -m*g+2*f2*(-s2/(3^0.5))+2*n2*(-((2/3)^0.5))+ 7*m*g/3 == 0,
    2*f2*(c2/(2^0.5)-s2/3+s2/6)-f3 ==0,

    c2*c2+s2*s2 == 1
    }
    Solve[eqn, {m, g, f1, f2, f3, n1, n2, c2, s2 }]

I tried this code, but it didn't work. The answer is like

out[16] = {}

Why it happen? And how can I solve it?