Chapter 3: Linear Motion (from Lecture Slides) Flashcards
Motion of objects is always described as relative to
Earth and Sun
Motion relative to the Sun is
Different from the motion relative to Earth
Speed
Distance covered per amount of time traveled
Speed equal to
Distance/time = v = d/t
Speed is
Units are meters per seconds
Average speed
The total distance covered divided by the total time and does not indicate various speeds along the way
Average speed equal to
Total distance covered / time interval = v = d/t
If known the average speed and time of travel
Total distance traveled = average speed x total time
Total distance equal to (Dtot = )
v(theta)t
Instantaneous speed
Speed at any instant
Instantaneous speed usually starts at
From a speed of zero then approach their maximum speed
Velocity
Speed + direction
A vector quantity description of both:
Speed (magnitude) of the object and direction of travel
Displacement (Formula) over time (Formula)
Theta (x) = Xf - Xi / (t) = tf - ti
Constant speed
“Steady speed” neither speeding up nor slowing down
Constant velocity
Constant speed and constant direction (straight line path with no acceleration)
Changing velocity
Speed, direction and or both
Acceleration formulated by
Galileo based on his experiment with inclined planes and rate at wich velocity changes over time
Slope downward
Speed increases
Slope upward
Speed decreases
No Slope
Does speed change?
Acceleration
Rate at which velocity changes over time
Acceleration (Formula)
Change in velocity / time interval = a = v(delta) / t(delta)
Acceleration involves a change in
Speed and direction or both
Any change in velocity implies acceleration
Speed up, slow down, turn or curved path
Galileo increased the inclination of inclined plane were
Steeper inclines result in greater accelerations
When the incline is vertical, acceleration is at
Maximum, the same as that of a falling object
When air resistance is negligible, all objects fall with
The same unchanging acceleration
Free-fall
Falling under the influence of gravity only with no air resistance
Free falling object on Earth accelerate at the rate of about
10 m/s^2 or 9.8 m/s^2
The velocity acquired by an object starting from rest is
Velocity = Acceleration x Time (V = at)
Once released upward, it continues to
Move upward for a time and then comes back down
At the object’s highest point, when it is
Changing its direction of motion from upward to downward, its instantaneous speed is zero
Free fall starts downward just as if it had been
Dropped from rest at that height
The distance covered by an accelerating object starting from rest is
Distance = 1/2 x Acceleration x Time^2
Under free fall, when acceleration is
10 m/s^2
Free fall (Formula)
d = 1/2at^2
Speed is a measure of
How fast and scalar (magnitude only)
Velocity is a measure of
Both how fast and in which direction
Vector
Magnitude and direction
Speed is the
Magnitude of velocity
