Answer: a) Moment = 200N.m
b) F = 500N
Explanation: Moment or Torque is the tendency of a body to rotate because of an aplplied force. It can be calculated as
[tex]\tau = F.r.sin\theta[/tex]
F is force applied
r is distance from the force to the point of rotation
θ is the angle formed between force and distance
a) Since F and r are perpendicular, θ=90°, sin90° = 1, so
[tex]\tau=F.r[/tex]
[tex]\tau=100(2)[/tex]
[tex]\tau=[/tex] 200
Torque caused by weight of the barrier at the pivot is 200N.m
b) Counterweight has the same torque as pivot: [tex]\tau=[/tex] 200
So, to find Force necessary to balance the weight:
[tex]\tau=F.r[/tex]
[tex]F=\frac{\tau}{r}[/tex]
[tex]F=\frac{200}{0.4}[/tex]
F = 500
It is necessary a force of 500N from the counterweight to balance the weight.
