Hi. This problem can be solved with the concept of moments. The moment of a force is the tendency of the force to cause rotation about the pivot, and is equal to the magnitude of the force multiplied by its distance from the pivot. On a stationary object, such as the lever in the question, the sum of all moments about the pivot is zero. Since the force F acts further from the pivot than the weight of the sand, its magnitude is lower. I have attached a simplified diagram, along with my solution to both parts. Please let me know if you have any further questions.
Hi. This problem can be solved with the concept of moments. The moment of a force is the tendency of the force to cause rotation about the pivot, and is equal to the magnitude of the force multiplied by its distance from the pivot. On a stationary object, such as the lever in the question, the sum of all moments about the pivot is zero. Since the force F acts further from the pivot than the weight of the sand, its magnitude is lower. I have attached a simplified diagram, along with my solution to both parts. Please let me know if you have any further questions.