Download Chapter 2 Outline

Chapter 2 Outline
I.
II.
Describing Motion
A. Motion
1. Motion and Position
a. Change in position
b. Reference point
2. Frame of Reference – the background motion is
measured against
3. Distance – how far an object has moved
4. Displacement – distance and direction in a straight line
from starting point to ending point
B. Speed - how quickly an object changes position
1. distance traveled per unit of time
2. s = d / t
3. Constant speed – speed stays the same the entire trip
4. Average speed – total distance divided by the total time,
used when speed is changing during trip
5. Instantaneous speed – speed at a given point in time
C. Graphing Motion
1. Time on X, distance on Y
2. Slope of line gives speed
3. Diagonal up, constant speed away from starting point
4. Diagonal down, constant speed back towards starting
point
5. Horizontal, no motion
D. Velocity
1. Includes both speed and direction
2. Changes – speed up, slow down, turn
E. Motion of the Earth’s Crust
1. Theory of Plate Tectonics
a. Earth’s plates move very slowly
b. 250 million years ago all one continent, Pangaea
Acceleration
A. Acceleration, Speed, and Velocity
1. Acceleration – rate of change in velocity
a. Change in speed, direction or both
b. Speed up, slow down, change direction
B. Calculating acceleration
1. acceleration equals change in velocity over time
2. a = VF – VI / t or
a = ∆V / t
3. units - m/s/s or m/s2
C. Amusement Park Acceleration
1. Designers calculate acceleration to:
- make sure downhill is steep enough that the rider
makes it up the next hill
- make sure the structure is strong enough to safely
handle the acceleration/force
III.
Motion and Forces
A. What is force
1. push or pull on an object
2. forces can cause changes in the motion of an object
(acceleration)
3. Net Force – when 2 or more force act on the same
object the combined force is called Net Force
4. Balanced forces
a. do not change motion
b. equal and opposite forces on the same object
5. Unbalanced forces change the motion
B. Inertia and Mass
1. Inertia – the tendency of an object to resist changes in
its motion
2. The velocity of an object stays the same unless a force
changes it
3. Objects at rest remain at rest, objects in motion
continue in the same motion unless acted on by an
unbalanced force.
4. Newton’s 1st Law of Motion – the law of inertia (see
above)
C. What happens in a crash
1. A car traveling 50 km/h stops suddenly, the person in
the car continues to travel at 50 km/h and smashes into
the windshield
2. This is why we have safety belts and airbags
a. The safety belt attaches the person to the car so
they stop with it
b. The airbag catches you when the safety belt does
not work quickly enough