Force and Motion

What is Force? A force can be a push or a pull. It is not something you can see or touch, but can see it in action. A force is something that can give an object motion! Force is measured in Newtons! (N)

A force can be used to... Change the direction of an object. You can pull the leash of your dog to make it change direction. Turn things. A natural force like wind can turn the blades of a wind turbine to generate electricity. Change the shape of something. A rolling pin can be used to reshape a ball of dough.

What are some different types of forces? There are contact, and non-contact forces. Non-contact forces act at a distance, and do not require physical contact between objects to function. Can you think of any non-contact forces? Contact forces occur between two objects that are in physical contact. Can you think of any contact forces?

Non-Contact Forces Gravity produces a force that pulls objects towards each other. It is the force that keeps the Earth revolving around the sun and it's what pulls you toward the ground Magnetism produces a force that can either pull opposite ends of two magnets together or push the matching ends apart. A magnet also attracts objects made of metal.

Contact Forces Normal Force Why does a book not go through a table, if gravity is such a strong force? Normal force is the force that a stable object exerts on another object. In this case, the table exerts a force on the book, to keep it stable.

Contact Forces Applied force refers to a force that is applied to an object such as when a person moves a piece of furniture across the room or pushes a button on the remote control.

Contact Forces Frictional force is the force caused by two surfaces that come into contact with each other. Friction can be helpful as in the friction that allows a person to walk across the ground without sliding or it can be destructive such as the friction of moving parts in a motor that rub together over long periods of time A Resisting Force, like friction or air resistance, can slow down or stop an object.

Contact Forces Spring Force- The Force exerted by pulling or compressing a spring Tension Force- The force applied on a wire or cable that is anchored on opposite ends

Representing Forces In science, we represent forces that are acting on an object using what we call a “Force Diagram”. Force Diagrams represent the direction and strength of the forces in action.The larger the arrow, the more force that is being applied.

Newton and Forces Using his knowledge of Forces, Isaac Newton developed three Scientific Laws which relate to force and motion. Newton based most of these laws on simple observations of force and motion! We will discuss these laws in more detail later, but for now we are going to make some observations of our own!

Let’s Have a Quick class 5 minute recess... Run, Jump, Throw a ball, do what you normally do at recess, but think about how the forces you are exerting are affecting motion! Using the scientific method, and your observations to develop your own “laws of force and motion”. What observations do you frequently see? How do forces affect moving, and non- moving objects? Try to draw one force diagram!