This can be answered using the formula of centripetal force. In the given problem, the centripetal force (40 N), mass (5 kg), radius (2 m) are all named, except for the speed. The formula is shown below:
F = mv^2 / r
Substituting the given values:
40 N = 5kg(v^2) / 2
80 = 5 * v^2
v^2 = 16
v = 4
Therefore, the correct answer is 4.0 m/s (4).