VELOCITY EQUATIONS HERE Intro to Motion + Speed and Velocity,
Section 2
Reference Point
chosen to make measurement convenient
ex. starting line for race
location compared to another
Distance and Location
standard units to determine distance
standard points to reference other points = reference points
ref. point on number line = 0, standard unit = meter
Displacement
change in position from reference point
distance = how far an object travels (measurement w/ no direction0 and displacement is how far an object is from where it started (change in position that includes direction)
distance can have a positive value, at the same time that displacement can be zero
Speed
Velocity
Speed Formula
Average speed includes the total distance and total time
Instantaneous speed = distance and time at a specific moment
Two measurements are needed to determine speed- distance and time
Speed = distance traveled during specific unit of time
Two measures are needed to determine velocity- displacement and time
displacement includes direction, so velocity also includes a direction (speed with direction)
velocity = displacement of an object during a specific unit of time
velocity can be an average velocity or an instantaneous velocity
Meters divided by seconds gives a unit of meters per second, m/s for speed
other units for speed can be used (km/h or mph...)
speed = distance travelled per unit of time or distance divided by time distance can be measured in meters, time in seconds
Velocity Formula
Delta x (Δx) is the symbol used for displacement
Delta (Δ) means "change in'. ad Δx means in "change in position"
Velocity is displacement per unit of time or displacement divided by time
Δx is calculated by final position minus initial positition
units for velocity are the same as for speed: m/s, km/h, mph
Time
v = Δx/t rearrange to use t = Δx/v or t = d/s
time or t is unknown
when speed or velocity and distance or displacement are known, time can be found
on graph, time is always on x axis
Instantaneous and Average Velocity
Average velocity will be different from any of the slopes of the lines on the graph any point on line will give an instantaneous velocity only)
slope of a line changes when the speed or velocity of an object changes (steeper the slope, greater the speed/velocity
Direction Changes
A direction change = represented when line on graph changes from positive slope to negative or vice versa
negative slope indicates object moving through origin, positive indicates object moving away from origin