Chapter 10 Flashcards
cart’s position
where the cart is
position variable
x
cart’s speed variable
v
speed variable
v
When is acceleration in direction of motion
when object speeds up
When is acceleration not in direction of motion
when object slows down
Displacement
How far the object ends up from original point, regardless of any motion in between starting and ending points
Displacement variable
(triangle)x
Graphical analysis of motion
position-time graphs and velocity-time graphs
What is on a position-time graph
slope is the object’s speed, object’s position is read from the vertical axis, time is x axis
What is on a velocity-time graph
Speed is read from vertical axis, slope is object acceleration, time is x axis
5 principal motion variable
- initial velocity (v0)
- final velocity (vf)
- Displacement (triangle x)
- acceleration (a)
- time (t)
In accelerated motion, when 3/5 principal motion variables are known, what can be solved with kinematic equations
remaining variables
Free fall
no forces other than the object’s weight is acting on the object
projectile
an object in free fall, but not falling in a straight vertical line
How to approach projectile problem
make two motion charts: vertical motion and horizontal motion
Slope is / (front slash)
movement is in the positive direction
slope if \ (back slash)
movement is in negative direction
Speed vs. Acceleration
Speed is how fast something moves, acceleration is how quickly speed changes
Can you tell which direction an object is moving with Acceleration
No, unless you know whether the thing is speeding up or slowing down
Velocity
Speed of something in a given direction
how to solve for final velocity
v0 + at
How to solve for final displacement
v0t + 1/2 a t^2
How to solve for v^2f
v0^2 + 2a(displacement)
What is the acceleration of an object in free fall
10 m/s per second towards the ground
The Acceleration of a free-fall object is always…
negative/down
What should you do if the projectile was launched at an angle
Treat the horizontal and vertical components of its motion separately
How to solve a projectile problem
Make 2 motion charts
Motion chart
Charts that have 5 principal motion variables on it
How to find vertical component of velocity at an angle
Multiply speed by sine of angle (this always works, as long as the angle is measured from the horizontal)
horizontal component of a velocity at an angle
multiply speed by cosine of angle (this always works, as long as the angle is measured from the horizontal)
How to calculate displacement on a velocity-time graph
Calculate area under velocity-time graph
Magnitude of accleration
How much acceleration (regardless of direction)
How to tell which line has a greater acceleration on a velocity-time graph
Steeper slope
How to rank speed
Don’t consider negative values
How to rank speed on position-time graph
Look at slope
Total distance object travel in all parts of motion
Add absolute values
How to get km/hr from m/s
multiply speeds by about 4
How to get miles per hour instead of m/s
1 m/s is equal to a little more than 2 miles per hour
When should you neglect air resistance
always, unless it is clear that air resistance is important (f.e. talking about terminal velocity)
What happens when you divide acceleration by 6
Distance/6
For horizontal and vertical motion charts for a projective, they must use the same _
time
