a) $-3 t^{2}+t=0$

Step 1 ：Solve the equation: \(-3t^2 + t = 0\)

Step 2 ：Factor out t: \(t(-3t + 1) = 0\)

Step 3 ：Set each factor equal to zero: \(t = 0\) and \(-3t + 1 = 0\)

Step 4 ：Solve for t: \(t = 0\) and \(t = \frac{1}{3}\)

Step 5 ：\(\boxed{t = 0, \frac{1}{3}}\)