Motion

Motion terms and their definitions: position:distance and direction from a reference point motion:change of position over a time interval example: 3.0 meters south of the flagpole distance directionreference point average speed:total distance traveled divided by the time interval

average speed: average speed = distance time total distance traveled divided by the time interval v = d t v = speed d = distance t = time vt d

vt d ex. A car travels 350 km in 5.0 hours. Calculate its average speed. v = d t = 350 km 5.0 hr v = 70 km/hr

ex. A car travels at an average speed of 60 km/hr for 720 km. Calculate the time of travel. vt d t = d v = 720 km 60 km/hr t = 12 hr

6 example Calculate the distance that a baseball moving at 120 feet per second can travel in 3.5 seconds. vt d d = t v = ( 3.5 s )( 120 ft/s ) d = 420 ft.

speed vs. velocity example of speed: 55 mi/hr example of velocity:55 mi/hr to the North velocity: speed in a certain direction A change of velocity is acceleration acceleration: a change of velocity over a time interval a = v f - v i t a = acceleration t = time v f = final velocity v i = initial velocity

a = v f - v i t A car accelerates from an initial velocity of 12 m/s to a final velocity of 42 m/s in 6.0 seconds. Calculate the acceleration of the car. ex. t = 6.0 s v f = 42 m/s v i = 12 m/s = 42 m/s - 12 m/s 6.0 s = 30 m/s 6.0 s a = 5.0 m/s 2 unit of acceleration: m/s 2

A car’s velocity changes from 64.0 m/s to 24.0 m/s in 2.0 seconds. Calculate the car’s acceleration. ex. t = v f = v i =6.0 s64.0 m/s24.0 m/s a = v f - v i t = 24.0 m/s m/s 2.0 s = m/s 2.0 s = a = m/s 2 negative acceleration: car is slowing down

Motion Graphs Two types: (1) Distance vs. Time (2) Speed vs. Time t d t d Distance vs. Time at restconstant positive velocity (CPV)

t v t v Speed vs. Time CPVpositive acceleration t v negative acceleration to a stop

t d t d Distance vs. Time at restCPV t d positive acceleration t d negative acceleration to a stop