Unit 1: One-dimensional Motion

Physics Foundations:

• vectors- magnitude/size AND DIRECTION is specified

• scalars- magnitude/size

Distance, Displacement, and Coordinate System:

• distance- total length of your path

  • always absolute value (can never be negative)
  • is a scalar quantity with units of distance

• displacement- net change in position

  • mentions change + direction
  • vector quantity with units of distance

• formula for displacement:

  

• position time graph- time is on horizontal axis & position is on vertical axis
  • ex of position time graph:

• coordinate system- what we use to describe position
  • origin = 0
  • defines directions with positive & negative numbers
• position- location of the object based on origin (0)
  • represented by x when referring to the position
• reference frame: point of view from which measurements can be made where all frames of reference are equally valid

Average Velocity and Average Speed:

• average velocity- is a vector

formula for average velocity:

• average speed- is a scalar

formula for average speed:

Velocity and Speed from Graphs:

• instantaneous speed- speed of an object at a particular moment in time
  • always absolute value (can never be negative)
• instantaneous velocity- velocity at a particular moment
  • can be positive (+) or negative (-)

• to be more exact you can choose a smaller displacement and shortter time interval

1. case where velocity of object does not change: average velocity

      1. in that case average velocity = instantaneous velocity

2. case where velocity of object is changing: motion on x-verses t-graph

      1. slope at any particular point = instantaneous velocity 2. get instantaneous rate of when x is changing with respect to time (find slope using closest unit of time before and after)

3. case where acceleration is constant

-kinematic formulas (explained further on)

-area under the velocity vs time curve = displacement

• Instantaneous vs average (in general)
  • average = over time
  • instantaneous = a given moment

Average and Instantaneous Acceleration:

• acceleration- change in velocity over time (is a vector quantity)

formula for acceleration:

• Velocity vs time graph
  • vertical axis represents the velocity of the object
  • slope of the velocity graph represents acceleration of the object

formula/example:

• slope is steep = object rapidly changing velocity
• slope is hallow = object not changing velocity as rapidly
• slope is negative/directed downwards = acceleration is negative
• slope is positive/directed upwards = acceleration will be positive
  • (area under velocity graph/curve = displacement of the object)

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• Average acceleration- rate at which velocity changes over a specified interval
  • \

• Unit: SI units of m/s^2
• is a vector quantity (can be positive or negative)
• speed of object remains same but changes direction = object accelerating
• velocity and acceleration vectors point in opposite directions = object is slowing down

• Instantaneous acceleration- rate at which velocity changes at a specific instance in time

Motion with Constant Acceleration

kinematic equations:

• earth’s gravity = 9.8 m/s^2
• acceleration is a constant line