Answer: The initial velocity was 30 m/s
Step by step:
Starting from the general formula for velocity at time t with acceleration a and an initial velocity v_0, set up the equation with all knowns, then solve for v_0:
[tex]v(t) = at+v_0\\v(5)=a\cdot5+v_0=-6\frac{m}{s^2}5s+v_0\\0\frac{m}{s}=-6\frac{m}{s^2}5s+v_0\\0\frac{m}{s}=-30\frac{m}{s}+v_0\\v_0=30\frac{m}{s}[/tex]
