#### Answer

The magnitude of the gravitational torque about the point where the beam is bolted into place is 12,500 N m

#### Work Step by Step

The gravitational torque comes from the center of mass of the beam and the weight of the worker at the far end of the beam. We can find the magnitude of the gravitational torque about the point where the beam is bolted into place.
$\tau_g = r_1\times F_1+r_2\times F_2$
$\tau_g = r_1\times m_1~g+r_2\times m_2~g$
$\tau_g = (2.00~m)(500~kg)(9.80~m/s^2)+ (4.00~m)(70.0~kg)(9.80~m/s^2)$
$\tau_g = 12,500~N~m$
The magnitude of the gravitational torque about the point where the beam is bolted into place is 12,500 N m