7 th Grade S2O1&2 Earth s Layers and Density concepts

Transcription

1 7 th Grade S2O1&2 Earth s Layers and Density concepts

2 Whether something floats in a liquid or not depends on the density of both! If the object placed into the liquid has a higher or larger density than the liquid----that object will sink!!!! So, of course---if the object placed in a liquid has a less density than the liquid s density, it will float. Remember that water has the density of 1.0 cm3 or 1.0 g/ml the terms are basically interchangeable.

3 If you are given a chart with numbers---you can determine the density---higher numbers = more dense materials.

4 Which color in the glass below is the most dense material? How to you know? Which color in the glass is the least dense? How do you know?

5 To find the volume of a regular object Simply measure length by width by height. Be sure you multiply them and not add them. If you are trying to find the volume of an irregular object---you must use water displacement. To compute the density of anything--- you MUST have the volume and the mass. Remember your heart divided in half. The top forms a M and the bottom a V.

6 Water displacement: Step one fill a graduated cylinder to a number deep enough to cover the object you are using. Write down the number where the water line is at. Step two Place the object into the graduated cylinder and mark the number where the water line rose to. Step three Subtract the first number from the second number and this is the volume of your object. (cm3) Mass the object on a triple beam balance. Write that down. To find the density of the object---mass divided by volume = g/cm3 not so bad, right!!

7 Bunch of earth stuff into a jar and then water added and shaken up: why do the objects land in the manner you see?

8 The answer---due to density. The most dense at the bottom and the lesser ones lining up one above each other with the least dense on top. Remember that cold air is more dense than warm air. Why? Because as air is heated up, the molecules will spread further apart making that warm air less dense than cold air. The cold air particles are still closer together and so MORE dense.

9 Why do particles an rocks sort the way they do around a stream or river bed?

10 When the river can no longer carry the load of the particles and/or rocks, they drop out. At the edges you will see the larger pieces out on the land further than the smaller ones that fall or are still slightly carried with the flow of the water.

11 Please consider that fact that if a river is moving faster with more force, particles may be moved further. Your 4 divisions of the Earth s interior are the crust, mantle, outer core and inner core. This is going from the surface to the center. Of course, the opposite would be inner core, outer core, mantle and crust. What is above the crust and also considered a layer---the atmosphere.

12 Remember that density is comparing how much stuff (molecules or atoms) are put into how much space. The space comparted would be the same size. See the boxes below. They are the same size but one (y)contains more atoms. Therefore, the box with more atoms is more dense. Why? Because density has to do with how many atoms/molecules are put into how much space.

13 Our Earth is organized with the most dense materials in the center and the least dense on the crust. What about the rest or some random order we find the materials in? Earth is moving and having volcanic explosions and/or earthquakes all the time this keeps items moved around into some random-looking effects. Remember that by nature when perfect all materials would line up with the most dense toward the bottom and work their way upward to the least dense.

14 How thick are the Earth s layers? Crust is the thinnest thick Mantle is the thickest about 2900 km thick Outer core is liquid and about 2300 km thick Inner core is solid and about 1220 km thick Also---the closer to the center of the earth we get, the temperature climbs higher and so things get hot! Hot! Hot!

15 Other notes of interest: Your mantle layer is like silly putty---can move and acts like a plastic. The inner core is make of iron. It is a solid ball The outer core is a liquid. The crust can be compared to the thickness of an egg shell of an egg or the skin covering a peach. It is very thin in comparison to the rest of the Earth s layers.

16 That is all folks hope this helps for your test.