Question

Help and explain please

Answer 1

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

$\tau = F.r.sin\theta$

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

$\tau=F.r$

$\tau=100(2)$

$\tau=$ 200

Torque caused by weight of the barrier at the pivot is 200N.m

b) Counterweight has the same torque as pivot: $\tau=$ 200

So, to find Force necessary to balance the weight:

$\tau=F.r$

$F=\frac{\tau}{r}$

$F=\frac{200}{0.4}$

F = 500

It is necessary a force of 500N from the counterweight to balance the weight.