1. Acceleration
Where
Acceleration is in the same direction as the object’s change in velocity

2. Direction of ∆V example
V1 = 40 mi/hr
V2 = 20 mi/hr
Because ∆V came out negative, the change in velocity is backward
Therefore the object is accelerating backward

3. Acceleration always has a direction.
We will not use the word decelerate to indicate direction

4. In what direction does a coin that is tossed straight up accelerate?
It is always accelerating down

5. A change in velocity example using numbers
V2= 10 m/s
V3 = 30 m/s
V1=30 m/s
Its change in velocity is down, therefore it must be accelerating down-even on the way up.

6. All objects in free-fall, near the earth’s surface, accelerate down at 10 m/s/s if we disregard air friction
Free-fall means that the only force acting on the object is gravity

7. What is the quarter’s acceleration at the top of its trajectory?
When the quarter is here
10 m/s2 down

8. Acceleration is the rate at which an object’s velocity changes

9. Again, we see that the object is accelerating down
V2 = 30 m/s
V1=30 m/s

10. Another example-are we there yet?
V1 = 0m/s
V2 = 10 m/s down
The change in velocity is down, therefore it is accelerating down.

11. Acceleration units Units are extremely important
Memorize the facts on pg 33 and 34 of my solution manual

12. An example of an object moving at constant speed and changing velocity would be a car rounding a curve at constant speed
There are no examples of an object moving at constant velocity with changing speed
Remember-Velocity is the speed and direction of an object

13. What is the acceleration of an object that starts off at 0 km/hr and is moving at 100 km/hr 10 seconds later?
forward

14. What is the acceleration of an object moving at a constant velocity of 100 km/hr?
Objects moving at constant velocity
cannot accelerate!

15. What is the distance fallen by an object in free-fall, 5 seconds after it is dropped?
For free-fall:

16. If you throw an object down, its acceleration is 10m/s2 after it leaves your hand
In this example, it will have an initial velocity greater than 0 m/s

17. Two traffic lanes side by side at a red light
V = 0 m/s
V= 5 mi/hr
For you, the initial velocity is not 0 m/s

18. Instantaneous velocity equation
Allows one to calculate the velocity at any given time

19. Newton’s first law of motion
An object at rest will remain at rest and an object in motion will remain in motion at a constant velocity, unless an unbalance force is applied to it.

20. A force is a push or a pull in a particular direction
It is a vector
We will use Newtons as units of force
Is a Newton

21. Add up all the forces acting on an object
Add up all the forces acting on an object. If the sum is 0 Newtons, the object cannot accelerate
It will remain at rest or continue to move at constant velocity

22. If an object accelerates, we know that there must be an unbalanced force applied to it
The moon accelerates as it goes around the earth
The earth accelerates as it goes around the sun