Unit 2: Kinematics

• Kinematics is the study of the motion of objects
• Frame of reference is the point of view from which you observe and describe an object's motion.
• All motion is relative to its frame of reference
• To describe position, you need a reference point and a coordinate system
• A reference point is the original point from which movement is determined
• A coordinate system allows you to specify the distance and direction.
• Scalars have magnitude only, no direction.
• Vectors are quantities that have both magnitude and direction.
• The resultant is the sum of several vectors or the displacement.
• No matter what order vectors are put in, the resultant length will remain the same
• Whenever describing a vector such as displacement, velocity, or acceleration, you must always include the angle and direction.
• Displacement is the straight-line distance between an object's final position and its initial position (final-initial).
• Displacement is a vector, while distance travelled is a scalar.
• Average velocity is the change in position (displacement) over the change in time, making it a vector quantity.
• The slope of a position-time graph is the average velocity.
• The velocity-time graph of an object moving at a constant velocity (no acceleration present) is a straight, horizontal line.
• In a velocity-time graph, the area would be the displacement.
• On a velocity-time graph to find the displacement and the velocity's changing, you can find the average velocity from the two points on the graph, or you could find the area of the triangle and the rectangle.
• On a position-time graph, at each point changing from up to down, the velocity is changing direction. At that point, the velocity is 0.
• On a position-time graph, an upward slope means a positive velocity and direction.
• Instantaneous velocity is the speed of an object at a particular point in time.
• On a velocity-time graph, if the velocity is negative, you must minus the area of the positive side from the negative to find the actual displacement.
• Negative, Changing Velocity, Fast to Slow

  
• Negative, Changing Velocity, Slow to Fast

  
• Positive, Changing Velocity, Slow to Fast

  
• If velocity is constant, the instantaneous velocity is equal to the average velocity,
• Average velocity is the change in an object's position over a time interval
• Instantaneous velocity is the velocity at a particular moment in time
• You find the instantaneous velocity by finding the average velocity at a certain point.
• To calculate speed, divide the total distance travelled by the time taken.
• Average acceleration is the rate of change of velocity with respect to time.
• When an object is moving at a constant velocity, the acceleration is 0.
• When velocity and acceleration have the same sign, the object is speeding up.
• When velocity and acceleration have opposite signs, the object is slowing down.
• Crossing the time axis means changing directions.
• The slope on a velocity-time graph is the acceleration.
• If the slope of a velocity-time graph is straight, the acceleration is constant.
• Instantaneous acceleration is the acceleration at one point in time.
• The velocity equations only work if acceleration is constant.
• free fall is the condition of unrestrained motion in a gravitational field.