Force is a phenomenon that we experience all the time, everyday. Its all around us. But how do we define force? We know it's there because we feel it, but is that really a valid excuse? Together we will define force and determine not only the different types of forces but also how they exists in our world.
Force is a push or a pull that an object experiences. If you hold a bowling ball and then let go, the bowling ball doesn't stay floating and it doesn't fly up. It falls down to the ground (or if you're not careful, it might fall on your foot!) Gravity is a type of force that we have known ever since we were young. The force of gravity pulls the ball down. It is an attractive force that exists between all objects.
This type of force when the you let the bowling ball go is called a long-range force or a field force because they don't involve physical contact between objects. We are more familiar with contact forces. Kicking a ball, pulling a wagon, and even pressing your finger on the mouse of you computer takes some force.
Each force has an agent; a specific, identifiable, and immediate cause. In the example with the bowling ball, the agent for the force of gravity if Earth's mass. When you kick a ball, the agent is your foot.
The easiest way to analyze the forces on an object is to sketch the situation identify the system, the agents and the direction of all the forces acting on the object. Here are some examples: (We use F to represent force.)
1. A book on a desk-->
2. Ball hanging from a rope-->
3. Ball held in your hand-->