Gold: Important concept. Very likely to appear on an assessment. Notes:Color Guide Gold: Important concept. Very likely to appear on an assessment. Blue: Supplemental information. Will not directly appear on an assessment. Red: Example. Copy if needed. White: Will be discussed by Mr. Williams.

Chapter 2: Motion in One Dimension Section 2: Accelerated Motion

Acceleration: a = ∆v/∆t = vf - vi Objects accelerate when they change their motion – either speed or directions (or both). Specifically, the change in velocity over time. An object accelerates when it changes its motion. This means: Speeding up Slowing down Changing direction Acceleration: a = ∆v/∆t = vf - vi tf - ti

The standard unit for acceleration is m/s/s. It is often written as m/s2 . With your partner… Use the acceleration formula to show how the unit of m/s2 is obtained. Explain, in plain speak, what the unit m/s2 means. m 1 s s x = _m_ s x s s2 m _s_ s

The magnitude of acceleration tells the rate of change of speed. Acceleration is the result of an unbalanced force. The sign of acceleration tells the direction of the unbalanced force.

Velocity vs Time The slope of a velocity vs time graph represents acceleration.

Falling Objects Free fall is a state of motion in which gravity is the only force affecting the object.

All objects free fall with an acceleration of -9.8 m/s/s. In other words, gravitational acceleration causes objects to speed up as they fall downward. In our studies, we will usually neglect air resistance until FRICTION is covered in more detail.

Dropped from some height. For any object that is: Dropped from some height. Thrown upward. Thrown horizontally. The acceleration is ALWAYS downward and constant at -9.8 m/s/s.

Each of these objects is in free fall. The velocity vs. time graph for any object in free fall has a negative slope.

We now have all the tools necessary to explore the Kinematic Equations. The Kinematic Equations describe the mathematical relationships that exist between an object’s motion. Displacement Velocity Acceleration Time

vf = vi + a∆t Note that: Velocity with Constant Acceleration: This equation does not require displacement. ∆t = (tf – ti) vf = vi + a∆t