Two farmers are trying to move a large rock that sits in a field. They use a long stick as a lever and a brick as the fulcrum, as shown in the diagram. They apply a force on the stick at the location shown by the arrow. However, the rock does not move. Which change would BEST allow the farmers to move the rock? A) Moving the brick closer to the rock. B) Moving the brick to the other side of the rock. C) Applying a smaller force at the same location on the stick. D) Applying an equal force at a location farther away from the rock.
Advanced Placement (AP) · College · Tue Nov 03 2020
Answered on
The principle behind a lever system is based on the concept of torque, which is the product of force and distance. The torque exerted on one side of the fulcrum must be balanced by the torque on the other side for the system to be in equilibrium.
In this scenario, if the rock is not moving, it suggests that the torque applied by the force on one side is not sufficient to overcome the torque on the other side (due to the resistance of the rock). To improve the situation, the farmers need to either increase the force or increase the distance from the fulcrum.
Therefore, the change that would BEST allow the farmers to move the rock is D) Applying an equal force at a location farther away from the rock. This increases the torque on the side where they are applying force, potentially making it more effective in moving the rock.