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Topic 4 (Young modulus, Hookes Law, and tensile strength)

Terms in this set (50)

Atoms
the building block of all molecules. The smallest part of an element
amu
atomic mass unit, (u), 1 amu = 1.66E-27kg; based on Carbon-12
Molecules
the smallest chemical unit of a substance that is capable of stable, independent existence.
What does the Kinetic Theory of Matter deal with?
the phase of matter; solid, liquid or gas. The molecules will vary in their arrangement from compact solids to dispersed gases
Kinetic Theory of Matter
1. The molecules of a substance are in constant motion.
2. Collisions between molecules are perfectly elastic.
Crystalline
regular arrangement of particles.
Amorphous
random arrangement of particles
Diffusion (solids)
the penetration of one type of particle into a mass consisting of a second type of particle.
True or false? Solids can diffuse
true
Cohesion
the force of attraction between molecules of the same kind. *Broken solids.
Adhesion
the force of attraction between molecules of different kinds.
Tensile strength
How easily a solid can be pulled apart.
How is the force applied when using the T.S. equation
normal to the cross sectional area
Ductile
the stretching of a metal into a wire
Malleability
This is when metals can be hammered or rolled into sheets.
Elasticity
The ability of an object to return to its original size or shape when external force removed.
Elastic limit
The point where the object is permanently deformed.
Stress=
F/A (internal force/change in area)
elongation strain=
Δl/l.
strain
The amount of deformation
Shear strain
pulled to the side
volume strain
ΔV/V (where ΔV=decrease in volume)
Hookes law
F=kx
Young's modulus
This is a way to compare elasticities
Y =
stress/strain
Y=
(FI)/(Δl*A)
Brownian Movement
The random movement of molecules in a liquid.
True or False? Cohesion and Adhesion forces exist in liquids.
True
Meniscus
The molecules of the water stick to the sides of the container and rise up slightly forming a concave shaped surface. (adhesion)
Viscosity
the ratio of shear stress to the rate of change of shear strain in a liquid or gas. (cohesion)
*Rate of flow of the liquid.
Surface Tension
The effect of molecules being attracted to each other at the surface. This causes a 'skin' on which very light object can be supported. It will cause free liquid to form a spherical shape.
Capillarity
The rising or falling of liquids in small diameter tubes due to adhesion. Liquids will do this until the upward force is equal to the weight of the liquid.
Melting
The molecules in a solid gain kinetic energy and flow forming a liquid.
Freezing
The molecules lose kinetic energy and become attracted to each other forming a solid.
True or false? Pressure can make a liquid form a solid regardless of its temperature.
true
Expansion
A gas will expand to equally fill its container.
Pressure
By increasing the number of molecules or increasing there kinetic energy (raise the temp), gases will increase the pressure on the walls of the container
Diffusion (gasses)
The movement of gases through a porous solid. (Oxygen and Carbon Dioxide diffuses through cells.)
Vaporization
The production of a vapor (gas) from a liquid or solid.
Evaporation
liquid to gas
sublimation
solid to gas without passing the liquid phase
Equilibrium Vapor Pressure
The pressure exerted by a vapor molecules in equilibrium with a liquid.
Boiling
The rapid vaporization that occurs when the vapor pressure of the liquid equals the pressure of its surface. Water will boil at a lower temp. if the pressure is decreased. (Water will boil sooner in Denver, but it will take longer to cook your potatoes.)
Plasma
A gas capable of conducting electricity; High temp. gases will form ions which conduct electricity. Usually occurs in stars and lightning. Most common phase of matter.
Common Properties of Fluids
Both liquids and gases are considered to be fluids.
Buoyant Force
The upward force any fluid exerts on an object placed in it. This is due to density.
Streamline Flow
How smooth a fluid will flow through a tube. It will be more smooth at wider parts than in narrow parts. If the tube is too
narrow, the velocity will be too high and cause turbulence.
Bernoulli's Principle
As water flows more rapidly through a narrow portion, the pressure is lowered. (Like how an airbrush works); The flow of a fluid through a tube, the sum of the pressure and the kinetic energy per unit volume of the fluid is a constant. (airplane wing)
By streamlining an object we can decrease drag. Turbulence increases drag. (bullets, cars)
decrease drag.
Turbulence
increases drag. (bullets, cars)
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