Chapter 6-9 Physical Science PDF

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Christian Draper...

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Chapter 6 What is a fluid? 

Gases and liquids that flow

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Fluids create friction against objects moving through them

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The faster the object the greater the friction

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It assumes the shape of the container

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Exerts no net sideways contact forces when at rest

Forces in a fluid: 

Friction

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Gravity

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Pressure (P = Force / Area)

Pascal’s Law: Pressure applied to any part of a bounded fluid transmits equally to every other part with no loss. The pressure acts at right angles to any surface in contact with the fluid

Hydraulic Systems: 

The force applied on the left side is distributed equally throughout the fluid

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If I push on the smaller cylinder with a force of 25 lbs, the force on the cylinder is 4 times larger

4 rules of unbound fluids 

Pressure depends on depth only and is greater and greater at depth

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Pressure is the same for all points at the same depth

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Pressure at a given depth is independent of direction

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Pressure is always perpendicular to the surface of a submerged object

Buoyant Force 

Objects seem to weigh less when submerged in water

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The mass of the object doesn’t change, so gravity remains the same

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Rules 1. Pressure is greater with depth 4. Pressure is always perpendicular to the surface

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Because forces in unbounded fluids increase with depth all objects in a fluid feel a net upward force called a buoyant force

Archimedes Principle: 

The buoyant force on an object equals the weight of the displaced fluid

Chapter 7 Reference Frames: 

Motion is always measured relative to something else

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Because of this we talk about objects as being “frames of reference: against which motion can be measured

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The everyday rules of transforming velocity measurements from one frame of reference to another is called Galilean Relativity

Frames of Reference: 

Can be either accelerated or non-accelerated

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If non-accelerated they are called inertial frames and are covered by the Special theory of relativity

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If accelerated they are non-inertial frames and are covered my the General theory of relativity

Reconciliation: 

The difference in points of view comes from the fact that the speed of light is the same for all observers. This is the second postulate of the Theory of Special Relativity.

Length contraction 

Moving objects are measured to be short

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No object can travel at the speed of light

Time Dilation: 

Moving clocks are seen to run slow

Chapter 8 Conserved Quantity 

Measurable

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May change form

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Has the same amount before and after the event

Conservation: 

Mass

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Total charge

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Linear momentum

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Angular momentum

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Total energy

Conservation of Mass: (mass is neither created nor destroyed; total mass is the same but changes form) 

Gasoline

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Forest fire

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Boiling water

Conservation of Charge: 

Rubbing a balloon on your head doesn’t create charge, but simply redistributes the existing charge.

Conservation of Linear Momentum: 

P = mass X Velocity

Conservation of Angular Momentum: 

Ring rotates about an axis

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The ring has mass (m) and rotates with speed (v). The radius of the motion is r

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The ring has angular momentum mvr.

Conservation of Energy: 

Energy can be neither created or destroyed

Chapter 9 Energy 

A quantity associated with the physical state position or motion of an object

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Types of energy (1) Kinetic-motion (2) Macroscopic (motion of objects) (3) Molecular (motion of molecules = thermal energy)

Mechanical Energy 

Kinetic Energy = Energy from motion (K. E. = mv^2/2)

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Types of mechanical energy i) Gravitational Potential Energy = weight X height ii) PE=mgh iii) Electrical Potential Energy = energy from charge seperation

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G is the acceleration caused by gravity

Work 

Work = force X distance

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Work is done when a force moves something

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Work occurs when energy changes forms

Internal Energy 

Temperature of a material (Thermal energy)

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Physical State (solid, liquid, gas)

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Chemical Potential Energy (molecular bonds)

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Elastic Potential Energy (shape of an object)

Heat transfer 

Radiation – The energy itself travels through space (sunrise)

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Convection – heat material and the material moves then gives up the heat (boiling pot of water)

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Conduction – Heat moves through the material but the material itself does not move or deform

Relativistic energy and mass-energy equivalence 

Mass and energy together are conserved

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Mass can turn into energy by the proportion of the speed of light squared

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E = mc^2...