Question 3
MotionA small metal ball is thrown vertically upwards from the top of a tower with an initial velocity of 20 m s−1. If the ball took a total of 6 s to reach ground level, determine the height of the tower [g = 10 m s−2]
- A.60 m
- B.80 m
- C.100 m
- D.120 m
Show the answer and explanation
Answer: A (60 m)
Explanation
Taking up as positive, displacement after 6 s = ut − ½gt² = 20 × 6 − 5 × 36 = −60 m. The ball ends 60 m below its start, so the tower is 60 m high.