Topic 4 - Materials

Question 1

Define Fluid.

Answer 1

Any Substance that can flow.

Question 2

Define Pressure.

Answer 2

The Force per Unit of Area.

Question 3

The Pressure Increases as what? (2)

Answer 3

*Contact Area Decreases
*Force Applied Increases

Question 4

Define Density.

Answer 4

The Mass per Unit Volume of a Material.

Question 5

State the Equation for Density.

Answer 5

Density = Mass/Volume

Question 6

Define Upthrust.

Answer 6

An Upwards Force Experienced by an Object caused by the Object Displacing Fluid.

Question 7

State the Word Equation for a Rising Object in terms of Forces.

Answer 7

Upthrust = Weight + Drag Force

Question 8

State the Word Equation for a Sinking Object in terms of Forces.

Answer 8

Weight = Upthrust + Drag Force

Question 9

State the Word Equation for a Tethered Balloon in terms of Forces.

Answer 9

Weight + Tension = Upthrust

Question 10

State the Equation for Pressure in a Column of Liquid.

Answer 10

Liquid Density x Height of Column x Gravity

Question 11

The Pressure at the Bottom of a Column of Liquid is Greatest. Why?

Answer 11

The Weight of the Water above it is Greatest.

Question 12

Define the Archimedes Principle.

Answer 12

States that the Upthrust experienced by an object is equal to the Weight of fluid Displaced.

Question 13

State the Equation for Archimedes Principle.

Answer 13

Upthrust = Density x Volume of Fluid Displaced x Gravity

Question 14

Define Viscosity.

Answer 14

A Quantity measuring the Internal Friction of a Fluid.

Question 15

Define Viscous Drag.

Answer 15

A Frictional Force between the Surface of an Object and a fluid, acting to oppose the objects motion.

Question 16

What effect does Low Temperature have on Viscosity in a Gas?

Answer 16

Viscosity decreases.

Question 17

What effect does High Temperature have on Viscosity in a Gas?

Answer 17

Viscosity Increases.

Question 18

What effect does a Low Temperature have on Viscosity in Liquids?

Answer 18

It Increases Viscosity, making it more resistive to flow.

Question 19

What effect does a High Temperature have on Viscosity in Liquids?

Answer 19

It decreases Viscosity, making it less resistive to flow.

Question 20

Define Yield Point.

Answer 20

The Extension increases rapidly for little increase in force. (Plastic Deformation)

Question 21

State Hooke’s Law.

Answer 21

The extension of an object is Directly Proportional to the Force Applied.

Question 22

State Stoke’s Law.

Answer 22

F = 6⊓nrv

Question 23

State the 4 Assumptions made when applying Stokes’ Law.

Answer 23

*Small
*Laminar Flow
*Slow Speed
*Solid Surface Sphere.

Question 24

Define Laminar Flow.

Answer 24

A State of Flow where layers of Fluid move together in Parallel with little or no mixing between Layers.

Question 25

What Causes Laminar Flow?

Answer 25

When a Fluid is flowing Slowly or an Object is Moving Slowly in the Fluid.

Question 26

Define Turbulent Flow.

Answer 26

Turbulent with fluid mixing layers.

Question 27

What Causes Turbulent Flow?

Answer 27

When a Fluid is flowing Quickly or an Object is Moving Quickly in the Fluid.

Question 28

Define Young Modulus.

Answer 28

Ratio of Stress-Strain (A Property of a Material that's in Tension or Compression).

Question 29

Young Modulus is the Gradient of what type of graph?

Answer 29

Stress-Strain Graph.

Question 30

State what Hooke's Law Describes.

Answer 30

The Stiffness of a Material.

Question 31

Define Stress and State the Equation.

Answer 31

-Force acting per unit of Cross-Sectional Area. - F/A

Question 32

Define Strain and State the Equation.

Answer 32

-The Ratio of Extension per Unit Length. -Change in L/L

Question 33

Unit for Young Modulus.

Answer 33

Pascals.

Question 34

State the Young Modulus Equation.

Answer 34

FL divided by Axl (Force x Original Length divided by Cross Sectional Area x Extension). or Stress/Strain

Question 35

An Object's Stiffness can be found by calculating the …of a Force-Extension Graph.

Answer 35

Gradient

Question 36

Define Limit of Proportionality.

Answer 36

The Object is Obeying Hooke's Law.

Question 37

Define Breaking Stress.

Answer 37

The Maximum Stress a Material can withstand without Fracturing.

Question 38

Define Elastic Deformation.

Answer 38

Object that returns to the Original Length after Force removed.

Question 39

Define Plastic Deformation.

Answer 39

Object that doesn't return to the Original Length after Force is Removed.

Question 40

Define Elastic Limit.

Answer 40

If Stretched Beyond this, the Object will not return to it's Original Length when Force Removed.

Question 41

Define Yield Point.

Answer 41

The Point on a Force-Extension graph at which a Material begins to rapidly extend without any additional Stress.

Question 42

State what a Stress-Strain Graph Describe.

Answer 42

The Behaviour of a Material.

Question 43

Define Ductile.

Answer 43

A Material that can withstand Large Plastic Deformation without Breaking.

Question 44

Define Brittle.

Answer 44

Tends to shatter when subject to Impact.

Question 45

Define Plastic.

Answer 45

A Material that Experiences a Large Extension as the Load is Increased.

Question 46

Define Tensile Strength.

Answer 46

Greatest Stress before Fracturing.

Question 47

Define Tough.

Answer 47

Able to absorb Energy without Failure.

Question 48

What is defined as having a Large Tensile Stress Value?

Answer 48

A Strong Material.

Question 49

What is meant by a Strong?

Answer 49

Force is Required to Break the Object.

Question 50

How do you Calculate Elastic Potential Energy from a Force-Extension Graph?

Answer 50

Area under the Gradient.

Question 51

Total Spring Constant in Series.

Answer 51

1/K1 + 1/K2

Question 52

Total Spring Constant in Parallel

Answer 52

K1 +K2

Question 53

An Object's Stiffness can be found by calculating the …of a Force-Extension Graph.

Answer 53

Gradient

Question 54

When an object is Stretched or Compressed, Work is Done on the Object. This is stored as ... ?

Answer 54

Elastic Potential Energy.

Question 55

How do you Calculate Elastic Potential Energy from a Force-Extension Graph?

Answer 55

Area under the Gradient.

Question 56

Explain and Describe what happens on a Force-Extension Graph once a Material has reached its Elastic Limit. (3) Clue - Loading/Unloading

Answer 56

-Loading and Unloading will not return to the Origin. -Loading and Unloading lines are Parallel due to Material's Stiffness Constant. -The Area between the Loading and Unloading Lines is the Work Done to Permanently Deform the Material.

Question 57

Why does a Skydiver opening a Parachute reach Terminal Velocity? (2 marks)

Answer 57

-Drag Force Increases -Terminal Velocity is reached when Resistance is equal to the Weight.