The effect of specific heat on energy invested
Question:

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?

 


 


2 People tried to answer this question

More energy should be invested in water heating, because its specific heat is higher.
More energy should be invested in sand heating, because its specific heat is lower.
More energy should be invested in sand heating, because its specific heat is higher.
More energy should be invested in water heating, because its specific heat is lower.



Comments:
1.  Levy Shmuel (2018-05-20 16:00:00)
comments from shmuel levy
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.
 

2.  Badarne Anwar (2019-05-20 16:00:00)
Anwar Badarne
Hii,

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. 


Good luck

3.  Dagash Wael (2020-05-20 16:00:00)
Good job !


Good job !

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 .

4.  Elfaks Sahara (25.05.2016 pm 08.45.51)
Feedback

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.

Good luck.
5.  Wolfson Helen (03.06.2016 am 12.28.19)
Response to Shmuel

Dear Shmuel,

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.

Best,

Helen

6.  Wolfson Helen (03.06.2016 am 12.35.41)
Respomse to Anwar

Dear Anwar,

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!

All the best,

Helen

7.  Wolfson Helen (03.06.2016 am 12.38.24)
Response to Dagash

Dear Dagash,

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.

Thanks for your contribution!

Helen

8.  Wolfson Helen (03.06.2016 am 12.45.33)
Response to Elfaks

Dear Elfkas,

Thanks for your comment!

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.

Thanks again and best regards,

Helen 



History of edits
Edited BY: Matan Maskit Edit Date: 2016-05-24 13:52:08
Edited BY: haya zinno birk Edit Date: 2016-05-24 08:18:03
Edited BY: Helen Wolfson Edit Date: 2016-05-24 06:22:50
Edited BY: Helen Wolfson Edit Date: 2016-05-24 06:20:54
Edited BY: shaul arama Edit Date: 2016-05-23 20:39:16
Edited BY: shaul arama Edit Date: 2016-05-23 20:38:56
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