Difference Between Gravity & Friction

Friction and gravity exist in every aspect of a person's life. For example, almost every movement you make, such as walking and running, involves friction. When you throw a ball up, gravity causes the ball to fall down. A person sliding a book across a table creates friction. Nevertheless, differences between gravity and friction also exist. Force affects gravity and friction in different ways.

Resistance defines friction. Friction consists of the resistance of one object in relation to another object with which it is in contact. Thus, friction is the force that opposes sliding motion, explains the Cornell Center for Materials Research. An example of friction involves removing a stain from clothing. You place detergent on a stained shirt, then repeatedly slide part of the shirt against the stained section. The friction eliminates the stain from the shirt.

Gravity is simply defined as what goes up must come down. Gravity is the natural force exerted between two objects, drawing them toward each other. Therefore, instead of an object such as an apple thrown in the air staying there or floating, it falls down. Weight is extremely important to gravity. Gravity always exerts a force equal to the weight of the object it is acting on. A cup remains on a table because the upward force of the table is equal to the weight of the cup, causing it to stay in place.

Pull affects gravity and friction in different ways. Gravity always pulls objects such as a desk, book or person down. Thus, when you jump, gravity causes you to land on the ground. Friction, however, doesn't pull objects down. Friction, however, doesn't pull objects down. In fact, unlike gravity, friction doesn't rely on a natural force. Instead friction occurs when something like a machine or individual pulls a sliding object in the opposite direction of another object. For example, when creating friction to start a fire, you repeatedly pull one stick up and the other down. Also, friction always acts parallel to the surface in contact because of the sliding action.

Friction consists of two types: kinetic and static. Kinetic friction involves movement, and static involves no movement. Static friction consists of two objects which have a large enough force to resist sliding. An example of static friction involves a computer on a desk. Kinetic friction consists of two objects moving relative to each other, like a sled on snow.