Question

A 47.0 kg uniform rod 4.25 m long is attached to a wall with a hinge at one end. The rod is held in a horizontal position by a wire attached to its other end. The wire makes an angle of 30.0 ∘ with the horizontal, and is bolted to the wall directly above the hinge.
If the wire can withstand a maximum tension of 1350 N before breaking, how far from the wall can a 69.0 kg person sit without breaking the wire?

Answer 1

Answer:

2.79 m

Explanation:

Use the static equilibrium condition, net torque actin on the system is zero.

$\sum \tau= 0$

$T(Lsin\theta)- Mg\frac{L}{2}-mgx=0$

solve for the distance of the person from the wall x

$x= \frac{TLsin\theta-Mg(L/2)}{Mg}$

now putting the values we get

$x= \frac{1350\times4.25sin30-47\times9.81\times(4.25/2)}{69\times9.80}$

= 2.79 m