4. Below are four equations, with the known quantities listed. Solve these equations to obtain an expression for T in terms of known quantities only. Do the same to obtain an expression for a. T-f=ma mg - T = m a N-mg cos 0 = 0 f = UN Known quantities: m, m, H, g,0 Unknown Quantities: T, a, N,f (these may not appear in your final expression for T and a)