Kinematics Flashcards
Kinematics
Motion in one direction
The first two important things
- The object of interest
2. The person describing the object
Reference frame
All motion is relative
Inertial reference frame
No acceleration
Non-inertial reference frame
Acceleration
Is there an ideal reference frame?
No, there is no universal reference frame that is not moving.
What does “speed is a scalar” mean?
It has a magnitude but no direction.
What does “velocity is a vector” mean?
It has a magnitude and a direction.
Order of magnitude
Power of 10.
What is the physical meaning of the slope of a position vs. time graph?
The object’s velocity.
What is the physical meaning of the slope of a velocity vs. time graph?
The object’s acceleration.
Velocity =
Displacement/time
∆x/∆t
Acceleration =
∆v/∆t
Motion
A change in an object’s position relative to a given observer during a certain change in time.
Motion is relative
The motion of any object of interest depends on the point of view of the observer.
Components of a reference frame
An object of reference
A coordinate system
A clock
Time or clock reading t (a scalar quantity)
The reading on a clock or another time measuring instrument.
Time interval Δt (a scalar quantity)
The difference of two times.
Position x (a scalar quantity)
The location of an object relative to the chosen origin.
Displacement ⃗d
A vector drawn from the initial position of an object to its final position. The x-component of the displacement dx is the change in position of the object along the x-axis.
Distance d (a scalar quantity)
The magnitude of the displacement and is always positive.
Path length l
The length a string laid along the path the object took (total distance).
Velocity ⃗v (a vector quantity)
The displacement of an object during a time interval divided by that time interval. The velocity is instantaneous if the time interval is very small (approaches zero) and average if the time interval is longer.
Speed v (a scalar quantity)
The magnitude of the velocity.
Acceleration ⃗a (a vector quantity)
The change in an object’s velocity ∆v ⃗ during a time interval ∆t divided by the time interval. The acceleration is instantaneous if the time interval is very small (approaches zero) and average if the time interval is longer.
Displacement (from velocity graph)
The area between a velocity-versus-time graph line and the time axis.
