Question Detail
Question
A ball is thrown vertically upward and returns to its starting point 8 seconds later. Neglecting air resistance, what was its initial speed? (g = 10 m/s²)
Correct Answer
Option B is the correct answer.
Detailed Explanation
The total time of flight for an object projected vertically upward and returning to its start point is T = 2v₀/g. Given T = 8 s and g = 10 m/s², we solve for v₀: 8 = 2v₀/10 => 80 = 2v₀ => v₀ = 40 m/s.
Hint
The total time of flight for a symmetric up-and-down trip is twice the time to reach the maximum height, which is related to initial velocity by t_up = v₀/g.