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A 10 m ladder's foot slides out at 3 m/s. How fast does its top fall when the foot is 6 m out?
A3/4 m/s
B9/4 m/s
C4/9 m/s
D3 m/s
Answer & Solution
Correct answer: B. 9/4 m/s
The height is 8 m, and x dx/dt + y dy/dt = 0 gives dy/dt = -(6 times 3)/8 = -9/4 m/s.
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