1. Unit 3: Kinematics & Free Fall
Sprayberry
Physics

2. Physics Comp Book UNIT 3: Kinematics & Free-Fall
Student will: compare algebraically the relationships between time, distance, velocity and acceleration; compare and contrast scalar and vector quantities.
Page Contents
17 kinematics, free fall
18 gravity, gravitational acceleration,
19 air resistance
19 kinematics formulas—x and y directions
20 Ex: solving a kinematics problem
20 Lab SUMUP:
* How tall is the stadium?

3. Frayer for kinematics kinematics kinematics:
All the ways to describe motion in a mathematical way:
describes the motion of objects without consideration of the causes leading to the motion
time =
displacement =
velocity-initial =
velocity-final =
acceleration =
kinematics
kinematics:
motion
math
Example Problem:

4. Kinematic Equations
Copy these into your comp book at the bottom of p. 19

5. Kinematic Equations - Ex #1
A car traveling with an initial velocity of 6 m/s, accelerates at 2 m/s2, for 6 seconds. What is the car’s final velocity?
LIST (3) Equation
(2) LABEL w/units (4) Solve
Are we working in the x or y direction?

6. Kinematic Equations - Ex #2
A car traveling with an initial velocity of 6 m/s, accelerates at 2 m/s2, for 6 meters. What is the car’s final velocity?
LIST (3) Equation
(2) LABEL w/units (4) Solve

7. Kinematic Equations - Ex #3
A car traveling with an initial velocity of 6 m/s, accelerates at 2 m/s2, for 6 sec. How far does the car travel?
LIST (3) Equation
(2) LABEL w/units (4) Solve

8. Galileo Galilei
Galileo formulated the laws that govern the motion of objects in free fall
Also looked at:
Inclined planes
Relative motion
Thermometers
Pendulum

9. Free Fall
All objects moving under the influence of gravity only are said to be in free fall
Free fall does not depend on the object’s original motion
All objects falling near the earth’s surface fall with a constant acceleration
The acceleration is called the acceleration due to gravity, and indicated by g

10. Acceleration due to Gravity
Symbolized by g
g = 9.81 m/s2
g is always directed downward
toward the center of the earth
Ignoring air resistance and assuming g doesn’t vary with altitude over short vertical distances, free fall is constantly accelerated motion

11. Free Fall – an object dropped
Initial velocity is zero
Let up be positive
Use the kinematic equations
Generally use y instead of x since vertical
Acceleration is g = m/s2
vi= 0
a = g

12. Free Fall – an object thrown downward
a = g = m/s2
Initial velocity ≠ 0
With upward being positive, initial velocity will be negative
vi 0
a = g

13. Free Fall - example
If a rock is dropped from a building, and it takes 18 seconds to reach the ground, how tall is the building?
LIST (3) Equation
(2) LABEL w/units (4) Solve