The 700N I got from counting what support forces the two points A and B have to support the plank without it rotateing or moving when the gril is not standing on the plank.
F=0
Na + Nb - Gp = 0
M=0
-Na x ra + Nb x rb = 0
Na x ra = Nb x rb
Nax 2.5m = Nb x 0.3m
2.5Na - 0.3Nb = 0
Making...
I counted the force which point B applys on the plank if the gril is not standing on it and i got to 700N.
I used that in this equition: Nb x Nr = Gg x r -------> rg = Nb x Nr / Gg
(700N x 0.3m) / (9.81m/s^2 x 48kg) = 0.44597m...
Is this Right :D?
Homework Statement
A plank is supported from two points. How far can a gril that weights 48 kg walk on the plank before the plank starts to rotate?. Middle of plank is its gravity point.
Picture: I have added a picture that might tell a bit more(not so good at English :/)...