Changes in Motion, Forces, and Direction Notes (page 38A and 39A) Some definitions: Speed: how fast an object is moving in meters/second (m/s) and is calculated by dividing distance by time Velocity: the direction an object is moving and how fast the object is moving in meters/second and is calculated by dividing distance by time AND describing the direction of the object Acceleration/deceleration: how fast an object is speeding up or slowing down and can be calculated by dividing distance by (time*time)

Changes in Motion, Forces, and Direction Notes (page 38A and 39A) Example: The Bugatti, which is the fastest car in the world, can travel 240 meters in 2 seconds. Assume the car is moving east. What is the speed, velocity, and acceleration of the car?

Changes in Motion, Forces, and Direction Notes (page 38A and 39A) Question: how do you know that an object is moving?

Changes in Motion, Forces, and Direction Notes (page 38A and 39A) Question: how do you know that an object is moving? A frame of reference is a plane that includes all interactions and motion (similar to the boundary of a system), includes units given by the observer and tells you that something is moving. Practice: How do you know your hand is moving as you write? What is your frame of reference?

Changes in Motion, Forces, and Direction Notes (page 38A and 39A) A force has both magnitude and direction and is the way potential energy is transformed into kinetic energy. All objects on Earth have forces working on them, even objects at rest. The net force of an object is the sum of all forces acting on the object. The more mass an object has, the more force it takes to move it.

Changes in Motion, Forces, and Direction Notes (page 38A and 39A) Balanced forces are equal in size, opposite in direction and have a net force of 0 Newtons. Objects in motion and objects at rest can have balanced forces acting on them. Balanced forces do not change an object’s speed or direction. Unbalanced forces are not equal in size AND/OR are acting in the same direction and have a nonzero net force. When the forces acting on an object are unbalanced, its speed and/or direction will change.

Changes in Motion, Forces, and Direction Notes (page 38A, 39A or 40A) Finding the net force for an object: Add up the arrows that are pointing in the SAME direction. After adding the arrows pointing in the same direction, subtract the forces pointing in different directions-this is the magnitude of your total net force. The direction of the net force will be direction that the greater force is pointing in. You will be answering the questions on the next slide on page 38B. You will find the net force, its direction and identify if the net force is balanced or unbalanced.