Moments A Level Maths Exam Question

Can someone explain how I can get the answer for 12a?
Original post by Matheen1
Can someone explain how I can get the answer for 12a?

I would suggest:

* resolve vertically to find Td
* Let x represent the distance of the CoM of the beam from A
Original post by old_engineer
I would suggest:

* resolve vertically to find Td
* Let x represent the distance of the CoM of the beam from A

Thanks did this to get x=1.2m but I need help with part b
Original post by Matheen1
Thanks did this to get x=1.2m but I need help with part b

Agree with x = 1.2m. For part b, you first need to work out the position on the beam of the new mass m. Then note that as the value of m is increased the tension Tc will decrease. The maximum allowable value of m will correspond to Tc = 0. More than that and the beam will tilt clockwise. Moments about D is the way to go.
Original post by old_engineer
Agree with x = 1.2m. For part b, you first need to work out the position on the beam of the new mass m. Then note that as the value of m is increased the tension Tc will decrease. The maximum allowable value of m will correspond to Tc = 0. More than that and the beam will tilt clockwise. Moments about D is the way to go.

Okay so first how do i work out the position of mass m
Original post by Matheen1
Okay so first how do i work out the position of mass m

The mass is m and you're told that its moment about C is 3.5mg.