Phys 151 Lab 1
Jenna Simone
Experiment 1 – Putting on the Ritz
Objective/Purpose: The purpose of this lab was to understand motion and how
graphical plots can represent motion.
Description of Experiment: For this experiment our group was assigned a specific graph
to discuss and then to act it out by walking the motion that was shown on the graph,
whether it be velocity or displacement.
Theory: The theory behind this experiment is to recognize and understand the five
motional variables: distance, displacement, speed, velocity, and acceleration.
Equipment: There is no equipment for this experiment
Method: For this experiment we reviewed the five motional variables in order to make
sure we understood their meanings. Then we were assigned a graph that as a group we
had to discuss and figure out how to act it out. One person from our group then acted out
the graph by walking the motion that was shown on the graph. We then reviewed the
graphs as a class.
Results: Below are drawings of the graphs to answer questions 1 & 2 in the lab. The first
graph is the corresponding velocity vs. time plot for the displacement vs. time plot in the
lab. The second graph is the corresponding displacement vs. time plot for the velocity vs.
time plot in the lab.
1.)
Displ.
+
Time
Vel.
+
Time
2.)
Vel.
+
Time
Displ.
+
Time
Conclusion: Upon completion of this lab our group has gained a better understanding
of the kinematic variables such as displacement made forwards and backwards, velocities
produced forwards, backwards, slow or fast and the graphical representation of these
actions. The experiment was successful because the visual experience was reinforced by
the graphs, which increased our understanding of the five motional variables and their
definitions.
Experiment 2 – Split Second
Objective/Purpose: To measure a person’s reaction time.
Description of Experiment: For this experiment we had to test each person’s reaction
time in our group by having one group member hold a meter stick, and the other person
holding their hand at the 50cm mark but not actually holding the meter stick. The first
group member holding the stick was to drop the stick at any time and the group member
holding their hand at the 50cm mark was supposed to catch the meter stick as soon as
their reaction kicked in. We then calculated their reaction time by computing the
difference between the 50cm mark and where the hand caught the stick.
Theory: When an object such as the meter stick is let go, it will fall straight to the
ground. Newton determined that this force is constant, so the object is moving with
constant acceleration. The following formulas prove this theory.
Acceleration: a = 10m/s^2 = rate of change of speed
Velocity: v = a.t = 10 t m/s
d = 1/2.10.t
t = 5t^2m
Equipment: meter stick
Method: Refer to the description of the experiment. Record reaction time by computing
the difference between the time the ruler was dropped and the time the ruler was caught
for each group member. Repeat the exercise for each group member at least three times
and then average out the distance traveled by using the formula above for d, which
indirectly measures reaction time. Since d is in meters and t is in seconds the formula can
be manipulated to give t = sqrt (0.2d)
Results: Below is the table of our group’s results:
Member
Initial
Position
.50m
.50m
.50m
.50m
.50m
Final
Position
.34m
.72m
.66m
.70m
.68m
Separation
d
.16m
.22m
.16m
.20m
.18m
Reaction time
t
Sqrt (0.2*.16) = .178
Sqrt (0.2*.22) = .209
Sqrt (0.2*.16) = .178
Sqrt (0.2*.20) = .2
Sqrt (0.2*.18) = .189
Mark Corpus
.50m
.50m
.50m
.50m
.50m
.60m
.59m
.57m
.60m
.60m
.10m
.09m
.07m
.10m
.10m
Sqrt (0.2*.10) = .141
Sqrt (0.2*.09) = .134
Sqrt (0.2*.07) = .118
Sqrt (0.2*.10) = .141
Sqrt (0.2*.10) = .141
Jenna Simone
.50m
.50m
.50m
.50m
.50m
.80m
.75m
.70m
.72m
.68m
.30m
.25m
.20m
.22m
.18m
Sqrt (0.2*.30) = .245
Sqrt (0.2*.25) = .224
Sqrt (0.2*.20) = .2
Sqrt (0.2*.22) = .2098
Sqrt (0.2*.18) = .1897
Meredith Clark
Conclusion: In comparing the data among our three group members, Mark has the
quickest reaction time, followed by Meredith, and then Jenna. It can be said that since
Mark has the quickest reaction time, and is a male, that gender plays a part. Since
videogames are more popular among men, and they are thought to improve hand and eye
coordination, so he might be more prepared for this type of exercise. Other
circumstances such as athletic ability and or experience might play a part as well. If
Mark has a background in soccer, tennis, baseball, hockey, etc. he would have a better
reaction time because it is a skill that is worked on during training. His reaction time is
significantly quicker then Meredith and Jenna. Even though Meredith is quicker then
Jenna, their numbers are closer in relation then comparing Mark and Meredith. That is
why gender could play a role in reaction time.
1.) Do You Want to be a Dollaraire?
Based on our data we would only bet someone if Mark was catching the bill. Jenna’s
reaction time is not quick enough and based on the five trials, she would have
dropped the dollar bill every time. Meredith’s reaction time is good, but not good
enough to catch the dollar bill. Mark has the most consistent data and using his trials
to judge whether his reaction time would be good enough, one can see that in several
instances he would have caught the dollar bill.
2.) Don’t Let Granny Get Behind the Wheel!
Reaction time is an important factor in deciding how far behind a car you should
drive because in the event you have to quickly put on your brakes to prevent an
accident, you need enough space to allow for a reaction time and the vehicle to stop.
Average Speed = distance/time
60mph = d / 0.26seconds
d = 15.6 miles
1 yard = 0.00056818 miles
____1 yard_____ = _______x________
0.00056818 miles
15.6 miles
15.6 = 0.00056818x
x = 27,456.0000552 yards