Question 8
MotionA bullet fired vertically upward from a gun held 2.0 m above the ground reaches its maximum height in 4.0 s. Calculate its initial velocity. [g ≈ 10 ms−2]
- A.10 ms−1.
- B.8 ms−1.
- C.40 ms−1.
- D.20 ms−1.
Show the answer and explanation
Answer: C (40 ms−1.)
Explanation
At maximum height the velocity is zero: 0 = u − gt, so u = gt = 10 × 4.0 = 40 m s−1. The 2.0 m height of the gun does not matter.