• Contrast two types of
electronic timing equipment
• Discuss units of time and
significant figures
• Relate accuracy and precision
to the measures of our lab
equipment
Describe the time shown on the
$15 stopwatch.
How fast can you start and stop the
stopwatch?
Describe the time shown on the
$350 timer from CPO.
Channel Setting Instructions for ResponseCard RF
1. Press and release the "GO" or "CH" button.
2. While the light is flashing red and green, enter the 2 digit
channel code (i.e. channel 1 = 01, channel 21 = 21).
Channel is 52
3. After the second digit is entered, Press and release the
"GO" or "CH" button. The light should flash green to
confirm.
4. Press and release the "1/A" button. The light should flash
amber to confirm.
How fast can you start and stop the
CPO timer?
Which stopwatch is more
accurate?
1. $15 stopwatch
2. $350 CPO timer
3. Other response
0%
$15 stopwatch
0%
$350 CPO timer
0%
Other response
Why do you think the two timers
have the same level of precision,
two decimal places?
1. Coincidence only
2. For a specific
reason
0%
Coincidence only
For a specific re...
Which of the following registers
the time corresponding to the
fastest object being timed?
1.067 s
0.960 s
0.250 s
0.179 s
0.100 s
s
10
0.
17
0.
0
s
0%
9
s
0%
0
0.
25
0
0.
96
7
06
0%
s
0%
s
0%
1.
1.
2.
3.
4.
5.
Two runners run a race and their
times are separated by 0.01
seconds. Who wins?
1. Runner A with a
time of 10.00 s
2. Runner B with a
time of 10.01 s
0%
ne
r
un
R
R
un
ne
r
B
A
w
ith
w
ith
a
a
tim
tim
e
e.
..
..
0%
Two runners run a race and their
times are separated by 0.01
seconds. Was the stopwatch
precise/accurate enough to
determine the winner?
1. YES
2. NO
0%
0%
Follow my instructions through
the use of the photogate timers.
Which situation displays the time
photogate A was blocked?
0%
0%
e
th
es
of
e
0%
4
0%
on
0%
N
1
2
4.4.
3
4
None of these
3
1.
2.
3.
4.
5.
2
3.
2.2.
1
1.
Which situation displays the time the
light at photogate B was blocked?
0%
0%
e
th
es
of
e
0%
4
0%
on
0%
N
1
2
4.4.
3
4
None of these
3
1.
2.
3.
4.
5.
2
3.
2.2.
1
1.
Which situation displays the time
it takes an object to pass between
the two photogates?
0%
0%
e
th
es
of
e
0%
4
0%
on
0%
N
1
2
4.4.
3
4
None of these
3
1.
2.
3.
4.
5.
2
3.
2.2.
1
1.
When both time lights are off and an
object passes through the photogates,
what, if anything, is recorded?
ll
o
ot
hi
ng
0%
N
o.
..
ft
he
A
0%
ab
B
fr
om
im
e
Ti
m
e
at
at
m
e
0%
to
...
0%
A
0%
A
Time at A
Time at B
Time from A to B
All of the above
Nothing
Ti
1.
2.
3.
4.
5.
Lab Sheet
If I were to perform an experiment in
which a car was down a ramp to
measure a variable, I would need to
recognize what all of the potential
variables could be.
• Brainstorm as many variables as you
can.
Types
Control OR Experimental
Independent OR Dependent
How many variables did you come
up with?
0%
0%
9
0%
8
0%
7
0%
6
0%
5
0%
4
0%
2
0%
3
1
2
3
4
5
6
7
8
9
1
1.
2.
3.
4.
5.
6.
7.
8.
9.
Lab
What are the variables in this experiment?
1.Distance between A & B
2.Position of A & B
Types
3.Weight
Control OR
4.Starting point
Experimental
5.Friction
Independent OR
6.Start technique
Dependent
7.Ramp angle
Motion
•
Aristotle (4th Century BC)
used logic incorrectly
1. Motion requires force
2. Heavier objects fall faster
3. Natural motion (up and
down) vs unnatural motion
(push and pull)
1500’s Galileo
•
Experiments are
better at testing
knowledge than logic
Galileo
1. Objects of different
weights fall to the
ground in the same
time
Galileo
• Force is needed to start movement but none after it
starts if friction is not present
?
Ball rolls farther as angle of inclination on the right is reduced
Galileo
• Speed Formula
• S=distance
time
Say the following in fewer words.
“She moves in a constant speed in a constant direction.”
“She moves at constant velocity.”
Formative assessments
• Teacher’s manual margin learning checks
with yellow backgrounds
Differentiate speed and velocity:
Speed is distance divided by time
whereas velocity is displacement
divided by time?
1. Correct
2. Incorrect
co
rr
ec
t
0%
In
C
or
re
c
t
0%
Differentiate speed and velocity:
Velocity includes direction and
speed does not.
1. Correct
2. Incorrect
co
rr
ec
t
0%
In
C
or
re
c
t
0%
Differentiate speed and velocity:
Speed is measured in m/s and
velocity is measured in km/h.
1. Correct
2. Incorrect
co
rr
ec
t
0%
In
C
or
re
c
t
0%
Differentiate speed and velocity:
the speed of an object is always
constant. The velocity of an object
can change.
1. Correct
2. Incorrect
co
rr
ec
t
0%
In
C
or
re
c
t
0%
Lab pink
sheet
What are the variables in this experiment?
1.Distance between A & B
2.Position of A & B
Types
3.Weight
Control OR
4.Starting point
Experimental
5.Friction
Independent OR
6.Start technique
Dependent
7.Ramp angle
Lab B-4
• Average Speed
– Distance / Time
A B distance (cm)
A B time (sec)
Lab B-4
• Predicting Speed (instantaneous)at
various Points on the Ramp
Wing of
Car
OR
Instantaneous Speed
Lab B-4
• Determine the relationship
between Slope and Speed
Distance &
time between
Photogates
AND
Average Speed
Lab B-4 Distance vs Time Graph
Distance
A-B (cm)
•Steeper the Slope
= faster the speed
Speed increases
down the ramp
Time A-B (sec.)
Galileo developed the concept of
acceleration
A=
v
t
In an automobile, what produces acceleration or deceleration in a car?
Accelerator, brakes, steering wheel….
a hill?
What limits (resists) acceleration?
MASS
a = 1 / mass
(inversely
proportional)
FRICTIONAL FORCE
AIR DRAG
A plane taking off…
1. Is an example of
acceleration
2. Is not an example of
acceleration
0%
ex
a
n
ta
no
Is
Is
an
ex
am
pl
e
m
pl
of
a
e
cc
of
...
e.
..
0%
A person walking 1.5 m/s along a
winding path…
1. Is an example of
acceleration
2. Is not an example of
acceleration
0%
ta
no
Is
Is
an
ex
n
ex
a
am
pl
e
m
...
...
0%
A car driving 88 km/h on a flat,
straight stretch of highway….
1. Is an example of
acceleration
2. Is not an example of
acceleration
0%
ex
a
n
ta
no
Is
Is
an
ex
am
pl
e
m
pl
of
a
e
cc
of
...
e.
..
0%
A bicyclist stopping at a stop sign.
1. Is an example of
acceleration
2. Is not an example of
acceleration
0%
ex
a
n
ta
no
Is
Is
an
ex
am
pl
e
m
pl
of
a
e
cc
of
...
e.
..
0%
Lab B-5
• Acceleration
Change in speed (cm/sec) = cm/sec2
change in time
(sec)
Speed
cm/s per s
or cm/s
A-B
(cm/sec)
s
Constant
Acceleration
(due to gravity)
WHY?
Time A-B (sec.)
Lab B-5
• Acceleration
Change in speed (cm/sec) = cm/sec2
change in time
(sec)
Speed
A-B
Constant
Acceleration
(cm/sec)
(due to gravity)
Time A-B (sec.)
OVERVIEW
A
Average Speed
(between A&B)
B
Instantaneous
Speeds (at A and B)
UNITS Distance
Displacement
cm
cm downhill or E
Time
Seconds
Change in Time
Time Interval
Speed
cm/sec
Acceleration
cm/sec2
Speed increase cm/sec per sec
over time
1. Which of these forces opposes
the motion of the car?
friction
weight
mass
gravity
ity
0%
gr
av
as
s
0%
m
ei
gh
t
0%
w
io
n
0%
fr
ic
t
1.
2.
3.
4.
1. Which of these forces helps the
motion of the car?
friction
weight
mass
gravity
ity
0%
gr
av
as
s
0%
m
ei
gh
t
0%
w
io
n
0%
fr
ic
t
1.
2.
3.
4.
•
Friction
Equation F=ma
2
Units
N=kg
m/s
is a force opposing motion
(N or kg m/s2)
• Weight is force that is the mass x the acceleration due to gravity
(F=ma or w=mg)
(N or kg m/s2)
Not the best choice because changing the mass does not change
the acceleration.
• Mass is not a force; it is the amount of matter in an object (kg)
• Gravity is the force creating the acceleration between two objects
The steeper the ramp, the _____ the
speed.
1. greater
2. less
3. There is no impact
0%
ss
im
pa
ct
0%
Th
er
e
is
no
le
gr
ea
te
r
0%
The steeper the ramp, the _____ the
acceleration.
1. greater
2. less
3. There is no impact
0%
ss
im
...
0%
Th
er
e
is
no
le
gr
ea
te
r
0%
What type of relationship is shown
in graph
1. direct
2. inverse
3. No relationship
N
o
re
l
at
io
n
sh
ip
e
ve
rs
in
di
re
c
t
0% 0% 0%
What type of relationship is shown
in graph
1. direct
2. inverse
3. No relationship
N
o
re
l
at
io
n
sh
ip
e
ve
rs
in
di
re
c
t
0% 0% 0%
What type of relationship is shown
in graph
1. direct
2. inverse
3. No relationship
N
o
re
l
at
io
n
sh
ip
e
ve
rs
in
di
re
c
t
0% 0% 0%
What type of relationship is shown
in graph
1. direct
2. inverse
3. No relationship
N
o
re
l
at
io
n
sh
ip
e
ve
rs
in
di
re
c
t
0% 0% 0%
Which correctly describes the
mathematical relationship of Newton’s
second law?
1.
2.
3.
4.
r..
.
e
e
th
es
of
e
on
N
ar
ar
e
se
ft
he
ll
o
A
co
rr
ec
t
co
F=
m
a
F/
m
a=
=F
/a
0% 0% 0% 0% 0%
m
m=F/a
a=F/m
F=ma
All of these are
correct
5. None of these are
correct
In the lab, which of the following calculation
showed a direct mathematical relationship for
acceleration with positive slope for the calculation
of Newton’s second law?
0%
0%
0%
...
F
th
es
e
x
m
N
on
e
of
a=
a=
m
/F
-F
0%
m
a=
/m
0%
F
a= F / m
a= m / F
a= m - F
a= m x F
None of these are
correct
a=
1.
2.
3.
4.
5.
A student is pedaling a bike by applying a net
force of 250 N. The mass of the bike and rider is
50 kg. Assuming no friction, what is the
acceleration of the bike and rider?
co
5
r..
.
kg
kg
e
,5
00
.2
kg
kg
0% 0% 0% 0% 0%
N
on
e
of
th
es
e
ar
12
50 kg
12,500 kg
.2 kg
5 kg
None of these are correct
50
1.
2.
3.
4.
5.
More graphical analysis and
equations
Sketch the graph as you think it
should be
Galileo vs. Newton
• Concerned with “how
things work?”
Concerned with “why things
work?” (CH. 10)
When a net force acts on an object,
the motion of the object does not
change.
1. Correct
2. Incorrect
co
rr
ec
t
0%
In
C
or
re
c
t
0%
When a net force acts on an object,
the speed of the object always
increases.
1. Correct
2. Incorrect
co
rr
ec
t
0%
In
C
or
re
c
t
0%
When a net force acts on an object,
the object’s direction of motion will
always change.
1. Correct
2. Incorrect
co
rr
ec
t
0%
In
C
or
re
c
t
0%
When a net force acts on an object,
the object accelerates in the direction
of the net force.
1. Correct
2. Incorrect
co
rr
ec
t
0%
In
C
or
re
c
t
0%
#7
A
B
C
D
0%
D
0%
C
0%
B
0%
A
1.
2.
3.
4.
#8
A
B
C
D
0%
D
0%
C
0%
B
0%
A
1.
2.
3.
4.
#9
A
B
C
D
0%
D
0%
C
0%
B
0%
A
1.
2.
3.
4.
#10
A
B
C
D
0%
D
0%
C
0%
B
0%
A
1.
2.
3.
4.
#11
A
B
C
D
0%
D
0%
C
0%
B
0%
A
1.
2.
3.
4.
#12
A
B
C
D
0%
D
0%
C
0%
B
0%
A
1.
2.
3.
4.
#13
A
B
C
D
0%
D
0%
C
0%
B
0%
A
1.
2.
3.
4.
#14
A
B
C
D
0%
D
0%
C
0%
B
0%
A
1.
2.
3.
4.