In the summer time, most people like spending time along the beach. At the beach, the cool water is much more inviting than the hot sand, even though the sun warmed them both up since the morning. Did you ask yourself why?
Different materials heat up in different rates. You may have heard the term "specific heat capacity", which is the amount of energy (heat) required to change the temperature of one mas unit of a substance by one degree celsius. Specific heat capacity, therefore, has units of energy per mass per degree. Each material has a different specific heat capacity. The specific heat of some materials is shown in the table below:
Specific Heat Table
Material
Specific Heat (j/kg 0C)
Air (nitrogen)
1.030
Aluminum
0.897
Sand
0.742
Diamond
0.510
water
4.186
Iron
0.449
Now that you know what specific heat capacity is, try answering the question below. You may find this video helpful.
Question:
In order to raise the temperature of the sand and water to the same level, where should one invest more energy?
The short introduction on the sea sand and water temperature is very good and serve as a good hint to the correct answer.
But the video was not clear to me. Showing 150g of sand at 23 degree and 150g of water at 23 degree has no meaning to the specific heat.
However the table with the specific heat values is very good and one can understand that for 1g and 1 degree you need more energy in the water relative to the sand.
I add Eilat to the map, the sand in the beach is very hot but the water temperature is always around 22 degree. Most of the visitors to Eilat fined it very unjoyful.
The subject of your question is
very interesting and you presenting it in the form that it is related to
everyday life.
Your introduction brief, helps to
answer the question and you wrote it attractively because we soon begin in
summer.
For me I like the video more than
the table because I love and understand better explanations through videos and
animations than graphs and tables.
For the points on the map: the
points of Helen and Haya are original and contribute to a better understanding
of the question.
But the point of Matan, I
felt that his point explains a new concept (desertification),
and this causes a confusion when we answer the question. About his
photo, it is nice but not helpful in resolving the question.
Ideas for improvement:
For example, you could add this
video that shows the specific heat of water.
It is an interesting
topic and close to our life , I like your question , it is short ,understandable
but we have to think deeply to solve it .
You video and
the points in the map help me to solve the question.
Your points
explain this phenomenon by using things that used every day in our life like the tools that used for the purpose of
cooking – the point of Helen, it helps a lot to understand the topic .
I like the
point of Shaul , there is something that first time that I know It, like the
cheese in the pizza and why it is staying hot a long time than another
components in the pizza , I had not though about this reason before .I think that without the points in the maps ,
I would choose the wrong answer.
Your video help us to solve but not a lot ,I think
that you have to heat up the sand and the water at
the same temperature for a certain time and then measure the temperature of
each of them to show to the students that there is a difference .
I think that
you must explain what is specific heat , and what is the meaning of the units
that appear in the table .
I would
suggest to you to add this animation that I have made to explain what is
specific heat .
Your subject
is very interesting and the introduction draws attention; it really makes you think
and get interested.
I enjoyed
reading the points on the map, each one of you presented it in a different way
and place. Thus, the reader understands that specific heat is everywhere; it’s
either in the kitchen, the food you eat or places you go to. Very creative,
good job.
*Improvements:
I was
expecting a question from a higher order thinking. I think that the text and
the table gave us the solution to the question. My advice: You can make the
question in a higher order thinking (application level) if you ask about sand
and other material in the table, such as Iron. Thus, the students can apply what they learned
about sand and water on sand and iron for example and we can see if they
understood the concept.
In addition,
I added a point on the map with a little background on specific heat and its
formula, I think it is important to introduce the students to the formula of
specific heat and its symbols.
Thanks for your comment. We liked your point on the map!
We decided not to modify the video, since it was only a "teaser" which should make you think, not formulate the answer for you. I saw that others commented that it helped them. We did add a short explanation on what heat capacity is. so persons not familiar with the subject can learn as well.
Thanks for the compliments, we're happy that you liked the question.
Following your comment to Matan, he changed his point's description so that now it's more connected to specific heat capacity. He also changed the photo.
We decided not to use the nice video you suggested, only because we were required to provide original materials. Thanks anyway!
Thanks for your comment. We implemented your advice and added an explanation of what heat capacity is. The video was not intended to show the answer, butn only to present the question.
Unfortunately, we could not use the animation since it's not our original material.
We concidered adding the formula, but didn't do so since we wanted to keep this at a level understandable to everyone, while forulas usually scare people off. Nevertheless, we're very happy that you raised the subject in your point!
Regarding the level of the question, you'll be surprised how people might find it tricky, especially those who are not familiar with the key concepts. For examples, one of the readers above mentioned that without the points on the map, he would have gotten the answer wrong. This question requires integrating knowledge from different sources: text, table and video. One last point- your suggestoin about Iron is good, but we wanted to show in the video something that would be both well known from daily life, and scientifically accurate. Thus, it would be difficut to find pure iron and measure its temperature for out needs.
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