Question

A ladder 5 m long is leaching against a wall . The bottom of the ladder is pulled along the ground away from the wall, at the rate of 2m/sec. How fast its height on the wall decreasing when the foot of the ladder is 4 m away from the wall –

• A. $\frac{4}{3}$ m/sec
• B. $\frac{8}{3}$ m/sec
• C. $\frac{10}{3}$ m/sec
• D. $\frac{6}{3}$ m/sec

Answer 1

Answer: (B)

$\frac{8}{3}$ m/sec

Answer 2

At time t

x² + y² = 5²

Ž 2x $\frac{dx}{dt}$ + 2y $\frac{dy}{dt}$ = 0

Given$\frac{dx}{dt}$, x, y, we have to find$\frac{dy}{dt}$