How Do You Make Things Move?

Things move primarily because of force.

Forces are fundamental to how objects interact and change their state of motion. According to physics principles, force is what makes things move. It has the power to initiate motion in a stationary object, stop a moving object, change its direction, or alter its speed. Furthermore, force can also cause objects to change shape.

Understanding Force and Movement

Movement doesn't just happen spontaneously; it requires an influence – a force – acting upon an object. This influence can vary in how it is applied.

Types of Forces

Forces can be categorized based on how they interact with objects:

• Direct or Contact Forces: These forces require physical contact between two objects for the force to be exerted.
  • Examples:
    • A person pushing a door open.
    • A foot kicking a ball.
    • The force of the ground pushing back on you when you walk.
• Forces Over a Distance: These forces can act on an object without touching it directly.
  • Examples:
    • Gravity pulling objects towards the Earth.
    • A magnet attracting iron filings.
    • Static electricity causing hair to stand on end.

The Role of Friction

While many forces initiate or change movement, friction is a force that often opposes it. Friction is the force between two objects in contact with each other that will resist an attempt to move them or resist ongoing motion. It's why things eventually slow down and stop moving unless another force keeps them going.

• Example: Friction between your shoes and the ground allows you to walk without slipping. Air resistance (a form of fluid friction) slows down a moving car or a falling object.

How Forces Affect Objects

A single force or multiple forces acting together can have several effects on an object:

• Starting motion from rest.
• Stopping motion.
• Changing direction.
• Increasing speed (acceleration).
• Decreasing speed (deceleration).
• Changing shape.

Understanding these forces is key to understanding why and how everything around us moves.

Force Type	Method of Application	Effect on Movement	Example
Direct / Contact	Physical touch	Starts, stops, changes speed/direction	Pushing a cart, kicking a ball
Over a Distance	No physical touch required	Pulls or pushes objects over distance	Gravity pulling a ball down
Friction	Between contacting surfaces	Resists movement, causes slowing down	Sliding furniture across a floor