Kinematics Flashcards
Linear Kinematics
Motion not considering outside forces
Distance
Amount of positional change
A scalar quantity (lacks direction)
Displacement
Distance an object moved from a reference point
Does not indicate how far an object traveled
A vector quantity having both magnitude and direction
Speed
How fast an object is moving, nothing about the direction of movement
Scalar quantity
Only positive
Average speed = direction traveled over time
Velocity
Involves direction as well as speed
Speed in a given direction
A rate of displacement (tells sign of velocity)
A vector quantity
Average velocity =displacement/time or s/t
Acceleration
The rate of change of velocity
Increase is positive and decrease is slowing down
Average acceleration = final velocity - initial velocity divided by time
Concavity
Concave up means positive acceleration
Concave down means negative acceleration
Uniformly accelerated motion
For every second an object is in the air there is a uniform change in velocity
Air resistance is neglected
Objects accelerate at a uniform rate due to acceleration of gravity
Object projected upward will be slowed at the same uniform rate due to gravity
Air resistance (Friction of air)
Lighter objects will be affected more, denser objects affected less
May stop accelerating and fall at a constant rate (all things reach this point eventually)
Laws of uniformly accelerated motion
Distance traveled and downward velocity can be determined for any point in time
Time it takes to reach max height is equal to time it takes to fall back to ground
Projectiles
Objects given an initial velocity and released
Follows a predictable path (parabola)
Gravity will negatively accelerate objects
Vertical affected by gravity
Horizontal not affected by gravity
Projectiles (gravity influences)
Maximum horizontal displacement (long jumper, shot putter)
Maximum vertical displacement (high jumper, pole vault)
Accuracy (shooting in basketball or soccer)
Vector of projectiles
Projective force and gravity
Projectiles with horizontal velocity
Horizontal velocity projects the objects same distance from the release point
Projectiles with vertical velocity (in the air)
Vertical velocity must be added
After the height of release
Projectiles with vertical velocity (upward velocity)
Negative acceleration by gravity
Reach zero velocity
Accelerate towards the ground
At release point has the same velocity it was given at release
Projectiles with vertical and horizontal velocities
Horizontal velocity remains constant
Vertical velocity subject to uniform acceleration of gravity
Horizontal distance of a projectile
Depends on horizontal velocity and time of flight
Time of flight depends on max height reached
Governed by vertical velocity of the object at instant of release
Magnitude of vectors for HDP is determined by?
Initial projection velocity vector
Angle of direction of this vectors
Angular Kinematics
Similar to linear Kinematics
Angular relates to rotary
Equations similar just different units
Angular displacement
Skeleton - system of levers rotating about fixed points when force is applied
Particles near axis have displacement less than those farther away
Angular displacement units
Degrees - used most frequently
Revolutions - 1 revolution = 360 degrees = 2pi radians
Radians - 1 radian = 57.3 degrees
Required for most equations
Theta symbol for angular displacement
Angular velocity
Rate of rotary displacement
The angle through which the radius turns divided by time
Angular acceleration
Alpha symbol - the rate of change of angular velocity
Relationship between linear and angular motion
All three have the same angular velocity
But linear velocity of the circular motion is proportional to the length of the lever
If angular velocity is constant?
The longer the radius, the greater is the linear velocity of a point at the end of that radius
Reverse is also true:
If linear velocity is constant, an increase in radius will result in a decrease in angular velocity
What if the radius of rotation decreases?
Linear velocity does change
Shortening the radius will increase the angular velocity, and lengthening it will decrease the angular velocity
Is there direct proportionality between linear velocity and the radius?
Yes
