Why does the sea mattress float on water?
 Question: Background: Density, or more precisely, the volumetric mass density, of a substance is its mass per unit volume. The symbol most often used for density is ρ (the lower case Greek letter rho), although the Latin letter D can also be used The density of an object determines whether it will float or sink in another substance. An object will float if it is less dense than the liquid it is placed in. An object will sink if it is denser than the liquid it is placed in. The water density anomaly is a concept in physics which describes a special phenomenon that characterizes the water: water in the solid state (ice) are less dense than liquid water. This is contrary to most solid-state materials. Thanks to BLOSSOMS video: "How Cold is Cold: What is Temperature? " http://blossoms.mit.edu/videos/files/english/how_cold_cold_what_temperature_english_flash_version   After watching the short video, please answer: Why does the sea mattress float on water?
3 People tried to answer this question

 `The water is cold and the sea mattress is hot.`
 Inside the sea mattress, there is air, which has a higher density than water.
 Inside the sea mattress, there is air, which has a lower density than water.
 `Inside the sea mattress there is cold air.`

very good :)

water are denser than air.

it doesn't explain Why the sea mattress float on water.

try to use the term "density" in order to explain Why the sea mattress float on water.

 Points on map:
 1. Wolfson Helen (13.06.2017 pm 09.27.19) Nice question! Hi Mor, I liked the question, it's especially relevant at this time when summer is approaching :) The background gives the reader a good understanding of the knowledge required to answer the question. If I may suggest some ideas for improvement, I woud introduce some changes to the animation: it would be nice f you added music and made it a bit more dynamic...additonally, there's currently no connection between theanimation and the water anomaly mentioned in the text (other than a photo of ice cubes immersed in water). I would add some graphic explanation of the water anomaly in the animation, and it's physical princples, since it's a subject which is quite complex.

History of edits
Edited BY: mor harush naim Edit Date: 2017-05-24 20:08:36
Edited BY: mor harush naim Edit Date: 2017-05-24 19:26:20
Edited BY: mor harush naim Edit Date: 2017-05-24 19:23:27
Edited BY: mor harush naim Edit Date: 2017-05-24 19:12:59
Edited BY: mor harush naim Edit Date: 2017-05-23 06:22:39
Edited BY: mor harush naim Edit Date: 2017-05-22 23:55:52