In trying to lift a heavy stone into a moving truck, a worker utilizes rope, a rug, and two long planks of wood. Identify what forces are at work in making it too hard for the worker to just lift the stone up on his back.
To identify the forces at work in making it difficult for the worker to lift the stone directly onto his back, we need to understand the concept of forces and how they affect the motion of an object.
1. Force of gravity: The weight of the stone exerts a downward force due to gravity. The force of gravity pulls the stone towards the Earth's center, making it heavy and difficult to lift.
2. Normal force: When the stone rests on a surface, such as the ground or the worker's back, the surface exerts an equal and opposite force called the normal force. In this case, while attempting to lift the stone directly onto his back, the worker would experience a significant normal force acting against his body, making it harder to lift the stone.
3. Friction force: When the worker tries to lift the stone using his back, the stone's weight creates a frictional force between the stone and the worker's back. This friction tries to prevent the stone from sliding or moving easily on the worker's back, requiring more effort to lift.
Now, the worker can use additional tools to overcome these forces and make it easier to lift the stone. For example:
1. Rope: By attaching the rope to the stone and pulling it from an elevated position, the worker can change the direction of the force required to lift the stone. Instead of lifting it vertically, the worker can exert a horizontal force, which may be easier to manage.
2. Rug: Placing the rug or a smooth surface under the stone reduces the friction between the stone and the ground. This allows the stone to slide more easily, reducing the force of friction when being loaded onto the truck.
3. Planks of wood: By using the planks of wood as ramps, the worker can reduce the angle of incline and distribute the stone's weight over a larger surface area. This decreases the force required to lift the stone gradually rather than lifting it directly, making it easier to load onto the truck.
So, the combination of gravity, normal force, and friction makes it difficult for the worker to lift the stone onto his back directly. But by utilizing the rope, rug, and planks of wood, the worker can manipulate these forces and make the task of loading the stone into the moving truck easier.