A pendulum bob is released from rest at a height of 78.4 m above the lowest point of its swing. Ignoring air resistance and taking m/s, what is its speed at the lowest point?
Answer and explanation
Correct answer: A. 39.2 m/s
- Step 1: Energy conservation: , so .
- Step 2: m/s.
Answer
39.2 m/s.
Why not the others: 1536.64 m/s: the square root is missing. 27.719 m/s: the factor 2 in is missing. 768.32 m/s: it multiplies and without using energy conservation.
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