Final answer:
The dart will reach maximum height at approximately 0.6 seconds.
Step-by-step explanation:
The maximum height of a projectile can be found by analyzing its vertical motion. In this case, the dart is thrown upward with an initial velocity of 18 ft/s at an angle of elevation of 59°.
Since the projectile's initial vertical velocity is 18 ft/s * sin(59°), we can determine the time it takes for the dart to reach maximum height using the equation:
t = (vertical velocity) / (acceleration due to gravity)
Plugging in the values, we have:
t = (18 ft/s * sin(59°)) / (-32.2 ft/s²)
Simplifying the expression, we get:
t ≈ 0.58 s
Therefore, the dart will reach maximum height at approximately 0.6 seconds.