Posted by **saud** on Saturday, October 29, 2011 at 10:10pm.

A 15 ft ladder leans against a wall. The bottom of the ladder is 4 ft from the wall at time t=0 and slides away from the wall at a rate of 3ft/sec.

Find the velocity of the top of the ladder at time t=2.

The velocity of ladder at time t=2 is ........ft/sec.

- Calculus -
**Reiny**, Sunday, October 30, 2011 at 12:03am
let foot of ladder be x ft from wall

let top of ladder by y ft above grouns

x^2 + y^2 = 15^2

2x dx/dt + 2y dy/dt = 0

so when t = 2, x = 4+6 = 10

y^2 = 225-100 = 125

y = √125 , and dx/dt = 3

2(10)(3) + 2(√125 dy/dt = 0

dy/dt = -60/(2√125)

= -30/√125

= appr. -.2.68 ft/sec

(the negative sign indicates the ladder is moving downwards)

- ap wizardry -
**Maroneys School of wizardry**, Monday, January 7, 2013 at 1:10pm
according to the ap wizardry handbook, using the demon spawn spell, the problem can be obliterated thorugh fire spitting dragons that originiate from the vave of JF.

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