# Physics

Q #2: (only other one I'm stuck on...)
A 10-kg ladder 2.5m long rests agaist a frictionless wall with its base on the floor 80cm from the wall. How much force does the top of the ladder exert on the wall?
I've found answers to similar questions on this site, but not close enough for me to figure this out. Thanks.

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1. A = angle from floor to ladder
get it from cos A = 0.80/2.5

Take moments around base of ladder

F * distance of top of ladder above floor
= Weight of ladder * half distance of foot of ladder from wall

F * 2.5 sin A = 10*9.8 * (2.5/2) cos A

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2. The answer is supposed to be 16.5N. I can't get it. Is angle A, 100deg? I took 0.80/2.5 = .32 and then cos (.32) = .9999deg.
And then in the final equation, for
sin A I got sin (100deg) = 98.4. This doesn't seem right.

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