A stone is dropped from a height of 45 m (take g = 10 m/s squared and ignore air resistance). With what speed does it reach the ground?
Answer and explanation
Correct answer: D. 30 m/s
- Step 1: Time of fall: , so s.
- Step 2: Speed m/s.
Answer
30 m/s.
Why not the others: 15 m/s: the average speed was used as the final speed. 3 m/s: this is the time of fall in seconds. 60 m/s: the speed was doubled.
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