alleryA 5 m ladder slides down a wall. Bottom moves outward at 1 m/s. Speed of top when bottom is 3 m from wall:
A3/4 m/s downward
B-3/4 m/s (top moves down at 0.75 m/s)
C0
D1 m/s
Answer & Solution
Correct answer: B. -3/4 m/s (top moves down at 0.75 m/s)
x² + y² = 25. 2x dx/dt + 2y dy/dt = 0. With x = 3, y = 4, dx/dt = 1: dy/dt = -3/4. Negative sign indicates y decreasing (top sliding down).
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