1. Free Falling Objects: Acceleration Due to Gravity
Kinematics Unit

2. Galileo discovered that objects fall to earth with a uniform, (constant), acceleration.
This constant acceleration is called the acceleration due to gravity. This constant is written as g = 9.81 m/s2 or
a = 9.81 m/s2.

3. YOU DO NOT USE ANY NEW ACCLERATION FORMULAE to solve these problems.
For all the problems a = 9.81 m/s2.
All of the previously mentioned formulae can be used because the object in question is accelerating uniformly.

4. RECALL:

5. Since acceleration is a vector, then the acceleration due to gravity must also be a vector, (have magnitude and direction).
If the object is dropped or falling
a = m/s2 .
If the object is thrown upwards
a = m/s2.

6. + Example 1: An object falls to the ground in 3.0s .
a. What is the object’s final velocity?
b. How far does the object fall? +

7. Example 2: A stone is dropped from a cliff 400m high
Example 2: A stone is dropped from a cliff 400m high. What is displacement of the stone after falling for 5.0 s?

8. Example 3: A ball is thrown vertically downwards at 30. 0m/s
Example 3: A ball is thrown vertically downwards at 30.0m/s. Determine the instantaneous velocity of the ball at 4.00 s.

9. Example 4: A stone is dropped from rest into a gorge
Example 4: A stone is dropped from rest into a gorge. Determine the distance that the stone falls during the third second of the fall.

10. Assignment: Read Text p. 54 – 62 Do p. 58 # 1-3 p.60 #1
Do Workbook p. 45 #25 – 33 (omit the question that requires you to use the CD that came with the book)
NOTE:
No class: Monday Sept. 28 (River Watch)
Quiz on Accelerated Motion and Graphing: Wednesday, Sept. 30
Accelerated Motion Lab due Wednesday, Sept. 30