Introduction to Force Lesson Goal: You will be able to find the net force acting on an object using force diagrams (free body diagrams) At the Bell: Get out the packet you picked up yesterday.

What is a Force? When you ride a bike, your foot pushes against the pedal. The push makes the wheels of the bike move. When you drop something, it is pulled to the ground by gravity. A PUSH or a PULL is a FORCE. So, a good definition for force is a push or pull in a particular direction.

Since force causes changes in the speed or direction of an object, we can say that forces cause changes in velocity, so…. Force causes acceleration!

Facts About Forces Forces are measured in Newtons (N) A Newton is the amount of force it takes to accelerate a 1 kg object 1 m/s/s or 1 m/s2

Balanced and Unbalanced Forces More than one force can act on an object at a time. The forces can push or pull in any direction. What happens to the object when the forces act depends on two things: → How strong the forces are → The direction of the forces When more than one force acts on an object, the forces combine to form a net force. The combination of all the forces acting on an object is the net force. Forces can work together or oppose each other.

Balanced vs. Unbalanced Balanced Force: When forces acting on an object are equal and in opposite directions. The object is not moving. Unbalanced Force: When forces acting on an object are not equal and opposing each other. This causes motion.

Finding the Net Force

Finding/Drawing Net Force (Find the Net Force and Represent it as an Arrow)

Finding Missing Forces

Force Questions What two things does force depend on? What has a greater force: Two objects hit a brick wall at the same speed. Object A is 10 kg and object B is 100 kg. A man pushes a box north with 70 N of force. A baby pushes the same box south with 5 N of force. What is the next force and which way will the box move?