A car starts 200.0 m west of town, and moves at 15 m/s east.1) write its best equation2) where will the car be at 10.0 s3) When will the car be in town
Determining Instantaneous Velocity
1) Graph the d/t data
2) Draw tangent to point of interest
3) Determine slope of tangent
Displacement vs Time
0
5
10
15
20
0 1 2 3 4 5 6 7 8 9 10
Time (s)
Dis
pla
ce
me
nt
(m)
Displacement vs Time
0
5
10
15
20
0 1 2 3 4 5 6 7 8 9 10
Time (s)
Dis
pla
ce
me
nt
(m)
Displacement vs Time
0
5
10
15
20
0 1 2 3 4 5 6 7 8 9 10
Time (s)
Dis
pla
ce
me
nt
(m)
Velocity vs Time Graphs
Velocity vs Time
0
5
10
15
20
25
30
0 2 4 6 8 10Time (s)
Ve
loc
ity
(m/s
)
a = sloped = xy or vtd = area
Velocity vs Time
0102030405060708090
100
0 1 2 3 4 5 6 7 8 9 10Time (s)
Ve
loc
ity
(m/s
)
a = slope = y/x = v/t = 62/5 = 12.4 m/s2
Velocity vs Time
0102030405060708090
100
0 1 2 3 4 5 6 7 8 9 10Time (s)
Ve
loc
ity
(m/s
) d = area under curve
Define each of the following
•DistanceDisplacement
•Speed Velocity
•Acceleration
Displacement vs Time
-15
-10
-5
0
5
10
15
0 5 10 15 20 25 30
Time (s)
Dis
pla
cem
en
t (m
)
A
B
C
D
Describe the motion for each series
Drill: •The velocity of a car is increased from 25 to 75 m/s west in 10.0 s. Calculate: a & d
vf = vi + at
d = vit + ½ at2
vf2 = vi
2+ 2ad
Displacement vs Time
-30
-20
-10
0
10
20
30
40
0 10 20 30 40 50 60 70 80
Time (s)
Dis
pla
cem
en
t (m
)
Displacement
Describe the motion between each interval
Displacement vs Time
0
2
4
6
8
10
0 1 2 3 4 5 6
Time (s)
Dis
pla
cem
en
t (m
)
A
B
C
D
Describe the motion of each series
Draw a position time graph for a person who walks
uniformly from the positive side of the origin back thru
the origin to the negative side. Repeat for the negative side.
Make the following conversions:
a) 10 m/s to km/hrb) 72 mph to m/s
1.6 km/mile
Draw a position time graph of a person who walks one
block briskly, waits at a traffic light, walks the next
block slowly, waits at another light, then runs the
last block.
A truck starts 400.0 m east of town, and moves at 12 m/s west Find the time & place where the car from the last problem & the truck will be at the same place
A car increases its velocity from 4.0 m/s to 36 m/s over 4.0 s.
Calculate: a & d
The same car slows from 36 m/s to 15 m/s
in 3.0 s. 1) Calculate the average
acceleration & dis
A car accelerates from 15 m/s to 25 m/s in
125 m. 1) Calculate its time &
acceleration
Drill:A car is coasting backwards at 3.0 m/s when its engine starts. After 2.5 s the car is
going 4.5 m/s. Calculate a & d
Motion Variables:•vi
•vf
•a• t•d
Make a chart
like the one to
the right
vi
vf
a
t
d
A car going 4.0 m/s accelerates at 3.0
m/s2 for 4.0 s. 1) Calculate: vf & d
A car slows from 44 m/s to 22 m/s
in 11 s.Calculate: a & d
Motion Affected by
Gravity
Gravity•A force of
attraction between two masses
Gravity•This force causes objects to accelerate towards each other
Gravity•The acceleration of gravity is relatively constant over the Earth’s surface
Acceleration of Gravity (ag or g)
9.81 m/s2
Down or (-)
GravityAny object in air will
have a vertical acceleration of
-9.81 m/s2
A ball is dropped from a 0.49 km cliff. The
acceleration of gravity is -9.8 m/s2.
Calculate: vmax & t
HW: A ball is thrown straight up at 19.6 m/s.
The acceleration of gravity is -9.8 m/s2. Calculate: hmax & tair
Drill: A ball is dropped from a ledge & lands
8.0 s later. Calculate: hledge & vmax
Homework•Problems: 27 – 30
•Page 103
Drill•A ball drops from 0.49 km.
•Calculate: tair & vmax
A man on the ground shoots a gun straight up & the bullet exits the barrel at
980 m/s. The acceleration of gravity is -9.8 m/s2.
Calculate its tair, vf, & hmax
A ball was dropped & landed at 70.0 m/s. The
acceleration of gravity is -9.8 m/s2.
1) Calculate: d & tair
A pumpkin was dropped from a plane & stayed in
air for 10.0 s. The acceleration of gravity is
-9.81 m/s2. Calculate: h & vmax.
Homework•Problems: 31 - 33
•Page 106
A cannon on a 2500 m cliff is fired straight up & the
ball exits the barrel at 0.98 km/s. The acceleration of
gravity is -9.8 m/s2. Calculate its tair, vf, & hmax
A ball is shot straight up to a height of 1.96 km. The acceleration of gravity is -9.8 m/s2.
Calculate: tair & vi
Drill: A car increases its velocity from 36 km/hr
to 72 km/hr in 5.0 s. Calculate: a & d
A car rolling backwards at 5.0 m/s accelerates at3.0 m/s2 for 4.0 s.
Calculate: vfinal & d
A car rolling backwards at 25.0 m/s accelerates at
5.0 m/s2 for 12.0 s.Calculate: vf & d
Homework•Problems: 58 - 60
•Page 112 & 113
Drill: A ball is thrown straight up at 9800 cm/s.
Calculate: tair & hmax
A ball is thrown straight down at 25 m/s & stays
in air for 4.0 s. g = -9.8 m/s2
Calculate: initial height& vf of the ball.
A ball is thrown straight up to a height of 49 m.
g = -9.8 m/s2
Calculate: vi & tair
Homework•Problems: 66 - 68
•Page 114
Drill: A ball is thrown straight sideways &
lands in 5.0 s. Calculate: initial
height & vmax down
A car rolling backwards at 5.0 m/s accelerates to 11
m/s forward in 4.0 s.Calculate: a & d during
that time.
A car going 36 km/hr slams on brakes, but still hits a tree at 6.0 km/hr after 1.0 s. Calculate: a & d during that time.
Displacement vs Time
-10
0
10
20
30
40
0 2 4 6 8 10
Time (s)
Dis
plac
emen
t (m
)
Velocity vs Time
-20
0
20
40
0 2 4 6 8 10
Time (s)
Vel
ocit
y (m
/s)
Drill: A ball is thrown straight up
and hits the ground in 6.0 sec.
Calculate: hmax & vi
Test Date•Wednesday
10/25/06
Classwork•Work Problem Section B on pages 56 & 57 in the gray Physics Book.
Drill: A car goes from 36 km/hr to 54 km/hr in
5.0 s. Calculate: a & d during that time.
Matching Stuff•Formulas
•Definitions
•Units
Definitions• Motion Position
• Velocity Speed
• Distance Displacement
• Time Acceleration
Units• Displacement
• Time
• Velocity
• Acceleration
40
30
20
10
0
-10
-20
-30
-401 2 3 4 5 6 7 8 9 10
Dis
plac
emen
t (m
)Displacement vs Time graph
A ball is thrown straight up at 49 m/s. Calculate: tair & hmax