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Motion and Forces (Forces (Forces transfer momentum (Momentum is conserved…

- - - - Forces on moving objects
        
        An object with forces acting on it can be moving at a constant velocity as long as those forces are balanced
        
        Balanced forces cannot change an object's speed or direction
        
        Unbalanced forces are needed to change an object's motion
    - - It is necessary to apply a continuous force to keep an object in motion
      - Galileo's Thought Experiment
        
        It does not take a force to keep an object moving
      - Newton's first law
        
        States that objects at rest remain at rest and objects in motion remain in motion unless acted upon by an unbalanced force
      - Inertia
        
        Resistance of an object to a change in the speed or the direction of its motion
        
        closely related to mass
  - - - Newton's second law
        
        States that the acceleration of an object increases with increased force and decreases with increased mass
      - Force equals mass times acceleration
        
        Force=mass*acceleration - F=ma
      - Mass and Acceleration
        
        Mass is a variable
        
        If the same force acts on two objects, the object with less mass will have the greater acceleration
    - - Centripetal force
        
        Any force that keeps an object moving
      - Circular Motion and Newton's Second Law
        
        If you know the size of the centripetal force acting upon the object, you can find its acceleration
  - - - States that every time one object exerts a force on another object, the second object exerts a force that is equal in size and opposite in direction back on the first object
      - Action and reaction pairs
        
        Force that is exerted on an object and the force that the object exerts back
      - Action and reaction forces versus balanced forces
        
        Balanced forces
        
        Forces acting on an object are balanced
        
        Action and Reaction
        
        acting on two different things
    - - can explain the motion of any object
  - - - momentum=mass*velocity - p=mv
    - - collision is where to objects exchange energy and momentum
    - - Conservation of momentum states that the total momentum of a system of objects does not change, as long as no outside forces are acting on that system
      - Two types of collisions
      - Momentum and Newton's Third Law
        
        Conservation of momentum is really just another way of looking at Newton's Third Law
- - - - Describing a postion
        
        Reference point
      - Measuring distance
        
        The way you measure depends on what information you want
    - - Describing motion
        
        A change in an object's position
      - Relative motion
        
        Depends on how it compares with observers motion
        
        Motion is described by using a frame of reference
  - - - Calculating speed
        
        Need to know both distance and time measurements
        
        Speed=distance/time - S=d/t
        
        Standard unit for speed is meters per second
      - Average Speed
        
        Speed is not constant
        
        Moment to moment speed is called instantaneous speed
      - Distance-time graphs
        
        A convenient way to show the motion of an object is by using a graph that plots the distance the object has traveled against time
    - - Velocity
        
        A speed in a specific direction
        
        Need to know speed and direction
        
        Velocity is an example of a vector
        
        A vector is a quantity that has both size and direction
      - Velocity versus Speed
        
        It is possible for two objects to have the same speed but different velocities
        
        Average speed depends on total distance traveled
        
        Average velocity depends on the total distance you are from where you started
  - - - The rate at which the velocity changes with time is called acceleration
      - Acceleration is a measure of how quickly the velocity is changing
      - Time=distance/Speed - t=d/S
    - - The change in velocity can be fund by comparing the initial velocity and the final velocity of the moving object
      - The time interval over which the velocity hanged can be measured
      - Calculating Acceleration
        
        Measured in meters per second over time, or m/s²
        
        Acceleration=final velocity-initial velocity/time - a=ⱽfinal-ⱽinitial/t
      - Acceleration over time
        
        Even a very small positive acceleration can lead to great speeds if an object accelerates for a long enough period
      - Velocity-time graphs
        
        Acceleration can change with time
        
        Can use a velocity-time graph