Forces and Balance
Forces are pushes or pulls from one object onto another. They can cause movement or prevent it from happening. Some common forces include gravity (pulling down toward Earth's center), air resistance (pushing against moving objects), and applied forces (when a person or object directly pushes another).
When objects aren't falling through surfaces, that's because of normal force. This is the force that holds things in place against other forces like gravity. For example, normal force keeps your coffee mug on the table instead of falling to the center of Earth!
Balanced forces occur when two forces are equal in size but act in opposite directions on an object. When forces are balanced, objects either stay still or continue moving at the same speed and direction. A good example is a perfectly balanced scale with equal weights on both sides - it doesn't tip in either direction because the forces are balanced.
Think about it: Ever notice how a book stays put on your desk? That's balanced forces in action - gravity pulls down, while the normal force of the desk pushes up with exactly the same strength!