NECO 2004 Physics · Question 32
A stone is dropped from the top of a tower of height 11 .25m. Calculate the time it will take to reach the ground. [g = 10]
Options
- A.1.00s
- B.1.50s
- C.2.25s
- D.2.50s
- E.3.00s
Answer: B. 1.50s
Explanation written with AI and checked against the answer key
Analyze the question: A stone is dropped (so initial velocity u = 0) from a height h = 11.25 m. We need the time t to reach the ground, with g = 10 m/s². Concept: For free fall from rest, use the equation of motion: h = ut + ½gt² Since u = 0: h = ½gt², so t = √(2h/g) Solution: t = √(2 × 11.25 / 10) t = √(22.5 / 10) t = √2.25 t = 1.5 s Check: h = ½ × 10 × (1.5)² = 5 × 2.25 = 11.25 m ✓ Answer: B. 1.50 s Tip: Watch out for option C (2.25 s). It is the value of t² and a common trap if you forget to take the square root. For "dropped" objects, always write u = 0 first, then use t = √(2h/g). Also, 2.25 is a perfect square (1.5²), which is a quick signal that the numbers were designed to work out neatly.AI can make mistakes. Report anything that looks wrong.
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