Free Falling Objects Acceleration Due to Gravity Kinematics

Free Falling Objects: Acceleration Due to Gravity Kinematics Unit

Ø Galileo discovered that objects fall to earth with a uniform, (constant), acceleration. Ø This constant acceleration is called the acceleration due to gravity. This constant is written as g = 9. 81 m/s 2 or a = 9. 81 m/s 2.

Ø YOU DO NOT USE ANY NEW ACCLERATION FORMULAE to solve these problems. Ø For all the problems a = 9. 81 m/s 2. Ø All of the previously mentioned formulae can be used because the object in question is accelerating uniformly.

RECALL:

Ø Since acceleration is a vector, then the acceleration due to gravity must also be a vector, (have magnitude and direction). Ø If the object is dropped or falling a = + 9. 81 m/s 2. Ø If the object is thrown upwards a = - 9. 81 m/s 2.

Example 1: An object falls to the ground in 3. 0 s. a. What is the object’s final velocity? + b. How far does the object fall?

Ø Example 2: A stone is dropped from a cliff 400 m high. What is displacement of the stone after falling for 5. 0 s?

Ø Example 3: A ball is thrown vertically downwards at 30. 0 m/s. Determine the instantaneous velocity of the ball at 4. 00 s.

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.

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