ANSWER:
18.3 m/s
STEP-BY-STEP EXPLANATION:
The acceleration formula is as follows:
[tex]a=\frac{v_f-v_i}{t}[/tex]
Since the final velocity is equal to 0, so we can solve for the initial velocity of the above, just like this:
[tex]\begin{gathered} -6.42=\frac{0-v_i}{2.85} \\ -v_i=-6.42\cdot2.85 \\ v_i=18.3\text{ m/s} \end{gathered}[/tex]
The starting speed is 18.3 m/s
