A worker pulls horizontally on a rope that is attached to a 10 kg crate that is resting on a rough floor. The coefficients of static and kinetic friction are 0.5 and 0.3 respectively. The worker pulls with a force of 45N. What is the frictional force exerted by the surface?
We did this in class and the answer was 45N but I do not understand why that is. Can someone explain?
Newton's Laws of Motion are three fundamental laws that describe the motion of objects in the presence of external forces. The first law states that an object at rest will remain at rest, and an object in motion will remain in motion at a constant velocity, unless acted upon by an external force. The second law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. The third law states that for every action, there is an equal and opposite reaction.
Newton's Laws of Motion can be observed in many everyday situations. For example, the first law can be seen when a person in a moving car suddenly stops and their body continues to move forward due to inertia. The second law can be seen when pushing a shopping cart - the harder you push, the faster it accelerates. The third law can be seen in activities like walking or swimming, where the action of pushing against the ground or water creates an equal and opposite reaction that propels the person forward.
Friction is the force that opposes motion between two surfaces in contact. It is caused by the roughness of the surfaces and the interlocking of their microscopic irregularities. Friction can either slow down or prevent motion, making it an important factor in everyday life and in understanding the motion of objects. For example, friction between the tires of a car and the road is necessary for the car to move, but too much friction can cause the car to skid or lose control.
The coefficient of friction is a measure of the roughness of two surfaces in contact. It is a dimensionless value that ranges from 0 (no friction) to 1 (maximum friction). The higher the coefficient of friction, the more force is required to overcome the friction and move an object. For example, a rough surface like sandpaper will have a higher coefficient of friction than a smooth surface like ice, meaning it will require more force to move an object across it.
There are several ways to reduce friction, including using lubricants, making surfaces smoother, and reducing the weight of an object. Lubricants like oil or grease create a thin layer between two surfaces, reducing the amount of direct contact and therefore reducing friction. Smoothing surfaces can also reduce friction by eliminating or reducing the interlocking of microscopic irregularities. Finally, reducing weight can also reduce friction, as there is less force pushing down on the surfaces in contact.