Motion
object changes distance
MOTION
_______ / ______ = speed
DISTANCE / TIME = SPEED
__________ + ________ = velocity
SPEED + DIRECTION = VELOCITY
Change in velocity
Acceleration
acceleration due to gravity on Earth
g = 10 m/s2
units: yards, meters, miles
DISTANCE
A girl walks 30 meters in 6 seconds. What is her speed?
30m / 6s = 5 m/s
Write a unit for velocity.
Examples: miles per hour (mph), kilometers per hour (kmh)
Increase speed = __________ acceleration
POSITIVE
Initial Speed in freefall
zero
No motion
A horse travels 75 kilometers in 3 hours. What is the speed of the horse?
75 km / 3 h = 15 km/h
You need to know _________, _________, and __________ to know velocity.
distance, time, direction
Decrease speed = ___________ acceleration
NEGATIVE
A rock falls for 6 seconds. What is the speed?
v = 60 m/s
v = gt = (10 m/s2)(6 s)
units: hours, seconds, days, minutes
TIME
What is the speed of a straight, slanted line?
constant speed
A race car is travelling 300 miles in 2 hours. What is the velocity?
Not possible - no direction
Three examples of acceleration:
1. ____________ acceleration
2. ___________ acceleration
3. change ________________
1. POSITIVE acceleration
2. NEGATIVE acceleration
3. change DIRECTION
A rock falls for 6 seconds. What is the distance?
d = 180 m
d = 1/2gt2 = (1/2)(10 m/s2)(6 s)2
units: miles per hour, km/h, seconds per foot
VELOCITY
A horizontal line = _______ speed
NO speed (stop)
A car has a starting position of 100 m and a final position of 20 m and moves in 10 seconds.
What is the velocity?
v = - 8 m/s
v = df - di / t = (20 m - 100 m)/10 s = -80 m/10s
___________ ___________ = no acceleration
Constant speed
If a rock falls 45 meters, its speed is:
v = 30 m/s
if d = 45 m, then t = 3 s
v = gt = (10 m/s2)(3 s)