1. Acceleration
Physics
1-D Motion

2. Acceleration
When velocity changes, we call that acceleration!
There are 3 ways in which velocity can change: slowing down, speeding up, or changing direction.

3. Equation for Acceleration
Acceleration = (final velocity-initial velocity) / time
a= v/t

4. Slowing Down?
When an object slows down, that can be called acceleration. ( + acc.)
It is usually called deceleration( - acc.)
It can also be called negative acceleration

5. Acceleration 3.1 Average and Instantaneous Acceleration
Section
Acceleration
3.1
Average and Instantaneous Acceleration
The average acceleration of an object is the change in velocity during some measurable time interval divided by that time interval.
Average acceleration is measured in m/s2.
The change in velocity at an instant of time is called instantaneous acceleration.

6. Acceleration 3.1 Average and Instantaneous Acceleration
Section
Acceleration
3.1
Average and Instantaneous Acceleration
The instantaneous acceleration of an object can be found by drawing a tangent line on the velocity-time graph at the point of time in which you are interested. The slope of this line is equal to the instantaneous acceleration.

7. Acceleration 3.1 Velocity and Acceleration
Section
Acceleration
3.1
Velocity and Acceleration
Solve for acceleration at 1.0 s:

8. Acceleration 3.1 Velocity and Acceleration
Section
Acceleration
3.1
Velocity and Acceleration
The slope of the line at 1.0 s is equal to the acceleration at that time.

9. Acceleration 3.1 Velocity and Acceleration
Section
Acceleration
3.1
Velocity and Acceleration
Solve for acceleration at 5.0 s:

10. Acceleration 3.1 Velocity and Acceleration
Section
Acceleration
3.1
Velocity and Acceleration
The slope of the line at 5.0 s is equal to the acceleration at that time.

11. Acceleration 3.1 Velocity and Acceleration
Section
Acceleration
3.1
Velocity and Acceleration
The acceleration is not constant because it changes from 3.4 m/s2 to 0.03 m/s2 at 5.0 s.
The acceleration is in the direction chosen to be positive because both values are positive.

13. Freefall
Any object which is moving and being acted upon only by the force of gravity is said to be "in a state of free fall." Free-falling objects do not encounter air resistance.

14. Free Fall 3.3 Acceleration Due to Gravity
Section
Free Fall
3.3
Acceleration Due to Gravity
After a lot of observation, Galileo concluded that, neglecting the effect of the air, all objects in free fall had the same acceleration. It didn’t matter what they were made of, how much they weighed, what height they were dropped from, or whether they were dropped or thrown.
The acceleration of falling objects, given a special symbol, g, is equal to 9.80 m/s2.
The acceleration due to gravity is the acceleration of an object in free fall that results from the influence of Earth’s gravity.

15. Falling Objects
Gravity is the force of attraction between any 2 objects, depending on their mass and distance apart g= acceleration due to gravity ALL objects free-fall at -9.8 m/s2 Negative sign because objects are accelerating toward the center of the earth..

17. Freefall Equations
To determine how fast an object is travelling: vf = g * t To determine how far a free-fall object travels: d = 0.5 * g * t2

18. Freefall on Graphs

20. Cause a change in an object’s velocity Cause acceleration
Forces
Cause a change in an object’s velocity
Cause acceleration

21. Balanced vs. Unbalanced
Balanced: Forces combine so the total force acting on an object is 0.
Unbalanced: Forces produce an acceleration

22. A force that opposes motion
Friction
A force that opposes motion
Friction depends on the surfaces in contact

23. Gravity
A force between two objects depending on the object’s mass and distance apart