College Physics Explore and Apply 2e Eugenia Etkina, Gorazd
Planinsic, Alan Van Heuvelen (Solutions Manual All Chapters, 100%
Original Verified, A+ Grade) All Chapters Solutions Manual Supplement
files download link at the end of this file.
Chapter 1 Introducing Physics 1-1
Chapter 1
Introducing Physics
Activities in this chapter are supposed to be done on the first day of class to put students at ease,
let them collaborate in groups and to reflect on the process that is depicted in the textbook in
Figure 1.3 on page 4 which is the logical flow of concept development that we follow
constructing all concepts in the course. We suggest doing 2 of the proposed activities, the first
one and one of the others.
1.1 What is physics? (Devising and using new models)
1.1.1 Tennis rackets
Class: Equipment per group: whiteboards and markers
Imagine that a new acquaintance (Miha) invited you to his house. You walk in and notice that he
has 10 tennis rackets in the hall way. You wonder WHY Miha would have those rackets.
Unfortunately, Miha does not speak English and cannot answer your question directly.
Work with your group members to come up with a plan to find out why Miha had 10 tennis
rackets.
Ask your students to get in groups and make a list of possible explanations (see possible
explanations in chapter 1 of the textbook). The most common ones are that Miha fixes rackets, or
has 10 children, or is a coach, or is a tennis racket thief. After the groups put their possible
explanations on the boards, ask them to share their ideas. After that, ask them how they can
figure out which one is the real one. This is when the students will come with what we call
“testing experiments”. Although, they might not look like experiments in physics, they need the
same actions. For example, if they think that Miha has 10 children, they might suggest looking
for different size shoes. The expect the shoes to be in the house if the children are there. This is
the prediction. What if they go to the house and find the shoes? Does it mean Miha has 10 tennis
rackets because of them or he can still be a repairman? But if they do not find any shoes there,
they might be more convinced that children are not the reason. Eventually, they will need to
agree that ruling out their explanations is easier than proving them. This is the goal of this
activity.
,Chapter 1 Introducing Physics 1-2
1.1.2 Cool glass
Class: Equipment per group: dry glass, ice-cold water, whiteboards, markers. Note: the higher the
humidity in the room, more clearly visible will be the outcomes of the experiments (in our experience
humidity of air should be 60% or higher). Alternatively, teacher may show slides with photos.
A teacher puts a dry and empty glass on the table and pours an ice-cold water into the glass.
a. Carefully observe the glass for few minutes. Describe in simple words what you observe.
Students will observe tiny water droplets that form on the outside wall of the glass. Make sure
they DO NOT use the word “condensation”.
b. Work with the members of your group to propose different explanations for the observed
patterns. Try to devise as many explanations as possible. Put them on the whiteboard.
In our experience, students propose up to four different explanations (see the first column in the
table below).
c. How can you find out which explanation is correct? In science we conduct testing
experiments. A testing experiment is an experiment whose outcome you predict before
conducting it using the idea under test. You do not need to agree with the idea but the prediction
of the outcome must be based on it. After you design the experiment and make predictions based
on all explanations that you devised, you will conduct the experiment and compare the outcome
to the prediction. Work with your group members to propose testing experiments that you can
run to test the proposed explanations. Try to propose as many as you can.
The most frequently proposed testing experiments are described in the table below.
d. For each testing experiment, make prediction for its outcome based on each explanation that
you proposed in b. Indicate any assumptions that you made when making predictions. (Note: The
best testing experiments are those that give different predictions for different explanations).
See the table below. Predictions are given at the crossroads of the explanations and the testing
experiments. Assumptions are indicated at the end of the testing experiments.
d. Perform testing experiments that you proposed in b. (if necessary, ask teacher for additional
equipment).
See table below. Outcomes of the testing experiments are described in the row after the
explanations.
e. Compare the outcomes of the testing experiments with the predictions that you made in c.
What can you say about the explanations under test now? Can you reject some explanations? Do
Etkina, Brookes, Planinsic, Van Heuvelen COLLEGE PHYSICS Active Learning Guide, 2/e © 2019 Pearson Education, Inc.
,Chapter 1 Introducing Physics 1-3
not forget to include the assumptions when making any judgements. Can you verify some
assumptions?
See table below. Judgments are given in the last row.
f. Think of the explanation that you were not able to reject as a new piece of knowledge. Can you
think of any application of this knowledge?
Students usually come up with the following ideas:
-Harvesting fresh water from air. Several simple devices that do this, and are actually used, can
be found on the internet.
-Drying air (for example in very humid places).
Table 1.2 with solutions
Testing exp. Testing exp. Testing exp. Testing exp. Testing exp. 5:
1: 2: 3: 4: Cover the
Use dry, Use different Put food Weigh glass glass filled
empty cooled cold liquid coloring in filled with ice- with ice-cold
glass (put (ex. oil) ice-cold water cold water water
glass in a Assumption: there Assumption: food Assumption: the
is no water in oil coloring goes cover does not let
fridge)
through the glass water through
but does not leave
(evaporate from)
water.
Explanation 1: There will be There will be There will be mf = mi There will be
Water from the glass seeped no water no water colored water water on
through glass wall outside glass outside glass on outside outside glass
glass.
Explanation 2: There will be There will be There will be mf = mi There will be
Water, which is inside the glass water on water on clear water on water on
wall, came out on the outside glass outside glass outside glass outside glass outside glass
Explanation 3: There will be There will be There will be mf mi There will be
Water escaped from the glass and no water no water water on no water
landed on the outside glass outside glass outside glass outside glass outside glass
Explanation 4: There will be There will be There will be mf mi There will be
Water from air collected on the water on water on water on water on
wall outside glass outside glass outside glass outside glass outside glass
OUTCOMES Water on Water on Clear water mf mi Water on
outside glass outside glass on outside outside glass
glass
JUDGMENT Reject 1,3 Reject 1, 3 Reject 1 Reject 1,2,3 Reject 3
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, Chapter 1 Introducing Physics 1-4
1.1.3 Popping the balloon
Class: Equipment per class: rubber balloons, needle, plastic bags (thin plastic bags for vegetables and
fruits work best), access to water (tap), bucket for catching water. Optional: small embroidery hoop (about
12 cm diameter)
A teacher is holding a fully inflated balloon. The teacher asks the students to observe carefully
while she pops the balloon using a needle.
a. Describe what happened when the teacher popped the balloon.
Students hear explosion-like loud sound.
b. What makes the sound so loud? Work in your groups to propose several explanations using
only simple words.
In our experience, students initially propose explanations 1 and 2 (see the first column in the
table below).
c. Propose testing experiments that you can run to test the proposed explanations. Try to propose
as many as you can.
The most frequently proposed testing experiments (TE) are TE 1,2, and 3 described in the table
below.
d. For each testing experiment, make prediction for its outcome based on each explanation that
you proposed in b. Indicate any assumptions that you made when making predictions. (Note: The
best testing experiments are those that give different predictions for different explanations).
See the table below. Predictions are given at the crossroads of the explanations and the TE.
Assumptions are indicated at the end of the TE.
d. Perform testing experiments that you proposed in b. (if necessary, ask teacher for additional
equipment).
See the table below. Outcomes of the TE are described in the row after the explanations (see TE
1,2, and 3)
e. Compare the outcomes of the testing experiments with the predictions that you made in c.
What can you say about the explanations under test now? Can you reject or revise some
explanations? Do not forget to include the assumptions when making any judgements. Can you
verify some assumptions?
After comparing the outcomes of TE 1,2, and 3 with the predictions, students realize that the
data obtained so far are inconclusive (it seems that none of the explanations is correct). At this
point the teacher suggest that maybe we should look more carefully at the original
Etkina, Brookes, Planinsic, Van Heuvelen COLLEGE PHYSICS Active Learning Guide, 2/e © 2019 Pearson Education, Inc.
