Need help with this question, the 'worked' solutions are useless.
I also don't understand the whole dilation of gravity thing
Thanks
(Image removed from quote.)
Torque is defined as a force multiplied by the perpendicular distant from that point to the force. (More technically it's the cross product of radius and force, this is why it's perpendicular). In the real world it's effectively a force that makes something want to rotate. In the picture the 20kg force wants to make the beam rotate around point P.
In our case the force from the 20kg mass is 20*9.8N (mg).
So we've decided that a torque is just a measure of how much something wants to rotate. Higher torque means something is wanting to rotate more. In the image above, would the left hand side 20kg mass produce a torque smaller than, equal to or greater than the torque on the right hand side?
Spoiler
Equal to, because only the perpendicular distance matters and it is the same in each diagram. Similarly, if we put the 20kg force above point P it would have a torque of 0, as it is not trying to rotate the beam.
So we now what our perpendicular distance is, it's just a matter of going T = r*F to get an answer of (hopefully, if I read the question right) 588Nm.
If this doesn't make any sense my apologies.
With the second part, I can't remember if you do summation of torques and forces.