Final answer:
The velocity of the object at its maximum vertical displacement is 0 m/s because gravity has reduced its upward motion to a temporary halt before it descends.
Step-by-step explanation:
When an object is tossed straight upward, the velocity of the object at its maximum vertical displacement is 0 m/s. At this point, the object has momentarily stopped moving upward and is about to start descending. This occurs because the acceleration due to gravity, which acts downward, continuously slows down the object as it ascends, until it reaches a point where the upward velocity is reduced to zero.
The maximum height reached by the object depends solely on the initial velocity's vertical component, as the upward motion is countered by the negative acceleration due to gravity. If we consider a scenario similar to a fireworks display where the initial vertical velocity component is 67.6 m/s, and we neglect air resistance, then a reasonable maximum height reached could be 233 m.