Rigid Objects in Equilibrium and Center of Gravity

[helen3743]

Thanks in advance--

Problem:
A woman who weighs 470 x 10^2 is leaning against a smooth vertical wall, as the drawing shows.
a) Find the force FN (directed perpendicular to the wall) exerted on her shoulder by the wall.
b) Find the horizontal component of the force exerted on her shoes by the ground.
c) Find the vertical component of the force exerted on her shoes by the ground.

I answered the problem, but I was wondering if I did it correctly.
I uploaded the drawing.

a) Fn(sin60)r1 = mgr2
Fn(sin60)(1.1+0.4) = 470(cos60)(1.1)
Fn = 198.99 N

b) 198.99 N

c) 198.99N + 470N = 668.99 N

Thanks!

 

[Doc Al]

a) Fn(sin60)r1 = mgr2
Fn(sin60)(1.1+0.4) = 470(cos60)(1.1)
Fn = 198.99 N

b) 198.99 N

Looks good to me.

c) 198.99N + 470N = 668.99 N

Why are you adding a horizontal force to the weight (a vertical force)?

Hint: You should be able to answer c) without any calculation.

 

[helen3743]

Hmm.. So I'm guessing it would be just 470N...?

Thanks again!

 

[Doc Al]

Hey, no guessing! The only downward force on her is her weight... so what must the upward component of the floor's force on her be for her to be in equilibrium?