Calculate the torque (magnitude and direction) about point O due to the force F in each of the cases sketched in Fig. E10.1. In each case, both the force F and the rod lie in the plane of the page, the rod has length 4.00 m, and the force has magnitude F = 10.0 N. (a)

Video transcript

Hi everyone today, we are going to calculate the magnitude and the direction of torque about the pivot point of a slender rod, which slender rod itself means that the weight of the rod is going to be negligible. So we know that to calculate a torque, the force has to be perpendicular to the distance from the pivot point, which in this case it is already perpendicular. So with the problem statement, it is known that there's five newton of force exerted. And at a distance of three m from the pivot point, which we can plug those values into our formula represented by the tower here equals to the distance are multiplied by the force exerted F. So we can plot those values in with the distance of three m and the fourth of five newton, which will then be equal to 15 newton times meter of torque. So now we can rule out option C. And also option D. So how do we know that the torque itself is going into or out of the plane? So to find the direction of the torque, we can use the right hand rule. So you have to point your fingers to the right hand in the direction of the distance or the art from the pivot point. So it will be this way and you have to curl your fingers to the direction of the force. So you want to curl your fingers downwards like. So, so with that then the thumb of your right hand will point in the direction of the torque. So when you point it this way, then your thumb will go into the plane of the page, which is going to be answer a right here. So let me know if you guys have any questions.