Vocabulary Mechanics – the study of the motion of
objects
Kinematics – Describing the motion of objects with words, diagrams, graphs and mathematical equations
Vocabulary Vector – a quantity (thing that can be
measured) which contains both a size (magnitude) and direction. Ex:
Scalar – a quantity which is completely described with a magnitude and has no associated direction Ex:
- Some things are by nature a scalar or a vector, some are DEFINED to be a scalar or a vector
Distance vs. Displacement vs. Position Distance – total path length travelled
Scalar
Displacement – length from starting to ending point. vector Points FROM starting point TO ending point
Position – measured from origin (you set coordinate system!)
Speed vs. Velocity Speed – “How fast” = distance / time
Defined to be a scalar Equation for AVERAGE speed:
Velocity – “how fast and in what direction” = DISPLACEMENT/time Defined as a vector (needs direction!) Equation for AVERAGE velocity:
Acceleration “how quickly something speeds up” AND/OR
“how quickly something changes direction” Equation for average acceleration:
Direction of acceleration (in 1-D)
Ticker-Tape Diagrams (aka particle diagrams) Dot represents the “center of mass” of the
object Like a strobe light picture – equal intervals of
time occur between each recorded dot Examples:
Vector Diagrams (aka motion diagrams) Use a picture of the object (sometimes a dot)
along with vectors to represent the motion of an object
Length of arrow represents size of vector quantity
Examples:
Position vs. Time Graphs Position on y-axis Time on x-axis Example with constant velocity
Slope of line =
Time (s)
Position (m)
0 0
1 3
2 6
3 9
4 12
5 15
Velocity vs. Time graphs Velocity on y-axis; time on x-axis Example – constant acceleration:
Slope of velocity vs. time graph =
Time (s)
Velocity (m/s)
0 2
1 4
2 6
3 8
4 10
Velocity vs. Time graph – finding displacement Displacement = AREA between line and x-axis
Area above the x-axis is positive displacement, area below is negative displacement
Example
Free-FallAn object is in free fall if its motion is only being affected by gravity
- air resistance is not a factor (negligible)- not being propelled by its own power
source- generally assumed to be on earth, unless
otherwise specified- can be going up OR down!
Examples:
Acceleration Due to Gravity Galileo’s Experiment (*demo/video demo)
Acceleration due to gravity (on Earth) =
Top Related