Download 14 - Plasticity

Name ___________________________________
Date _______________
Lab Period _____
Lab Day ______
Plasticity
Data Table
Number Procedure
1
2
3
4
5
6
7
8
Result (solid or liquid)
QUESTIONS:
1.
Answer questions # 1 – 5 in complete sentences.
2.
3.
4.
5.
6.
A
B
C
D
7.
A
B
C
D
8.
A
B
C
D
Lab #14 Plasticity
INTRODUCTION:
The mantle of the earth, the layer below the crust, is said to be plastic. Plastic means that the
mantle sometimes exhibits properties of a solid and sometimes exhibits properties of a liquid.
Since no one has reached the mantle, scientists can only guess as to its actual make-up.
All earthquake waves can pass through the mantle, which means it is a solid (S-waves cannot
pass through liquids). Yet the tectonic plates of the earth “float” on the mantle, moving by
convection currents in the mantle (convection occurs in fluids). Scientists conclude that the
mantle, at its high temperatures and pressures, can act as both a solid and a liquid. On the
earth’s surface, some materials act in the same way. A group of them, called non-Newtonian
Fluids, are used to make “slime” and other disgusting toys.
PROCEDURE:
Your teacher will provide you with a measured quantity of cornstarch in a plastic beaker.
Water, and possibly food coloring, will be added until the right consistency is obtained.
Your teacher will help you with the consistency.
1.
Slowly, push your finger (or silverware) into the mixture and record whether the
material acts as a solid or liquid.
2.
Quickly, jam your finger (or silverware) into the mixture and record whether the
material acts as a solid or liquid.
3.
Try to “pull” the mixture away from the sides of the beaker with your silverware.
4.
Pour a pancake size amount onto your lab table. Poke the surface rapidly with your
finger and record whether the mixture acts as a solid or a liquid.
5.
Try to pick up the mixture from the table with your hands and record whether the
mixture acts as a solid or a liquid.
6.
Try to roll a small amount into a ball in your hand and record whether the mixture acts
as a solid or a liquid.
7.
Stop rolling the ball of the mixture and record whether the mixture acts as a solid or a
liquid.
8.
Play with the mixture as much as time and your teacher permits, leaving time to clean
up.
QUESTIONS:
1.
Before the addition of water, was the cornstarch a solid, liquid, or gas?
2.
What phase was the water before it was added to the cornstarch?
3.
How is the mixture of cornstarch and water similar to the earth’s mantle?
4.
How is the mixture of cornstarch and water different from the earth’s mantle?
5.
How might the plasticity of the earth’s mantle influence the movement of the earth’s
lithospheric (tectonic) plates?
6.
Which is suggested by the occurrence of higher than average temperatures below the
surface of the earth in the area of the Mid-Atlantic Ridge?
A)
B)
C)
D)
7.
the existence of convection cells in the mantle
the presence of heat due to orographic effect
a high concentration of magnetism in the mantle
the existence of a thinner crust under mountains
Which diagram below best illustrates the theory of mantle convection currents at the
Mid-Atlantic Ridge?
A
B
C
D
8.
The diagram below represents a partial cross section of a model of the Earth. The
arrows show inferred motions within the Earth.
Which property of the oceanic crust in Regions F and G is a result of these inferred
motions?
A)
B)
C)
D)
The crystal size of the basaltic rock decreases constantly as the distance from the
mid-ocean ridge increases.
The temperature of the basaltic rock increases as distance from the mid-ocean
ridge increases.
Heat flow measurements steadily increase as the distance from the mid-ocean
ridge increases.
The age of the igneous rock increases as the distance from the mid-ocean ridge
increases.