A pendulum consists of an object of mass 1.21kg tht hangs at the end of a massless bar a distance 1.28m from the pivot point calculate the magnitude of the torque due to gravity about the pivot point?

The torque is the component of the weight that is perpendicular to the bar. So when the bar hangs vertically down, parallel to the force of gravity, there is no torque. If the bar makes an angle "A" with the vertical then the component of weight perpendicular to the bar would be mgSin(A) and the torque would be mgLSin(A) , where m= 1.21 kg, and L = 1.28m, g=9.8m/ss , so all you need is the angle "A".