A bullet shot straight up returns to its starting point in 10 s.What is the initial speed of the bullet?
A) 98 m/s
B) 49 m/s
C) 25 m/s
D) 9.8 m/s

Question

Quizplus · Accepted Answer

When a bullet is shot straight up, its final velocity will be zero since it comes back to the starting point (assuming no air resistance). Therefore, we can use the formula for displacement:
Δy = V₀t - ½gt²
where Δy = 0 (since the bullet returns to its starting point), V₀ is the initial velocity, t = 10 s, and g = 9.8 m/s² (acceleration due to gravity).

Simplifying the equation, we have:
0 = V₀(10 s) - ½(9.8 m/s²)(10 s)²
0 = 10V₀ - 490
490 = 10V₀
V₀ = 49 m/s

Therefore, the initial speed of the bullet is 49 m/s, which is answer B).

A Bullet Shot Straight Up Returns to Its Starting Point