Material Flashcards
equation for density
Density(p)=mass(m)/Volume(v)
equation for upthrust
Upthrust= Density of fluid x volume x gravity
Unit for denisty
kg/m^3 (kgm^-3)
How to use a vernier Caliper
1)close the jaws and check for zero error. Zero error has to be accounted for in end result.
2)At zero mark, the reading of the main scale
3) the vernier scale with the main scale
4) add together and take account for zero error
Accuracy
how close you are to the true value
sensitivity
how small a division a piece of equipment can measure to
precision
how similar repeated values are
measuring density of irregular objects
1)measure mass with a top pan balance
2)measuring the volume with a displacement can/measuring cylinder
Liquid densities
1cm^3 = 1ml
tap water = 1gcm^-3 =1000kgm^-3
Upthrust definition
upthrust is the upward force on an object from the material it is in
Archimedes principle
Upthrust is the same as weight of material displaced
upthrust equation
density of fluid (pf) x volume of fluid displaced(vf) x accel due to gravity(g)
if an object is floating and no movement
Upthrust of fluid = weight of object
pfvfg=povog
pfvf=movo
if object is floating on the surface is partially submerged
density of fluid > denisty of object
Uf=Wo
if object is fully submerged
volume is the same therefore the densities of the submerged object and material around is the same.
pf=po
what is terminal velocity?
Terminal velocity is the constant velocity that is reached when Upthrust + viscous drag = weight
RF=0
Free body diagram of falling
^ Force due to drag
I
I Upthrust+Drag=weight
O
I ^
I I upthrust
I
v Weight
Free body diagram of rising
^ upthrust
I
I
I Upthrust=Drag+weight
O
I I Drag
I v
v Weight
Equation for stokes law
to calculate viscous drag
F=6xpixradiusxviscosityxv
Conditions for stokes law
- Small
- Spherical object
- low speed
- laminar flow
CPAC 4-
1) Drop a ball bearing of known density and diameter through washing up liquid of unknown viscocity
2) Record distance and times between three markers as shown using the split time function. Determine terminal velocity
3) Repeat each ball multiple times to get more accurate results
4) At terminal velocity , Weight = Drag + upthrust
5)Drag=Weight - upthrust
6pinrv=4/3pir^3Pirong-4/3pir^3Pliquidg
this equates to
n= 2r^2g(Piron-Pliquid)
—————————–
9v
laminar flow definition
Laminar flow is a type of airflow around an object that is smooth and consistent, with a minimum of disturbance and separation
Turbulent flow definition
Turbulent flow is a type of fluid flow in which the fluid undergoes irregular fluctuations, or mixing
equation for volume of
a) cuboid
b) sphere
C) cylinder
a) basexheightxdepth
b)4/3pir^3
C)pir^2xdepth
state weight in terms of density
weight = density x volume x gravitational field strength
what is the equation for work done in limit of proportionality
workdone = 0.5 x force x extention (this is always = amount of elastic potential energy stored)
what is the equation for work done out limit of proportionality
workdone = 0.5 x stiffness x extention^2
Force extention graph gradeint =
n/m (newton metre)
stress equation
Force(n)/Area(m^2)
Define density
The mass per unit of volume
Define Upthrust
Upthrust, or buoyancy, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object
Viscous drag
Viscous drag is a force of friction that is present when a solid object moves through a fluid
define stress
Force per unit area
define strain
strain refers to the relative deformation or change in shape and size of elastic, plastic, and fluid materials under applied forces.
Young modulus experiment
1.Measure the diameter of the wire with a micrometre screw gauge or digital callipers. Take at least 3 readings and find an average
2.set up the apparatus so the wire is taut. No masses should be on the mass hanger just yet
3.Measure the original length of the wire using a metre ruler and mark a reference point with tape preferably near the beginning of the scale eg. at 1 cm
4.Record initial reading on the ruler of the reference point
5.Add a 100 g mass onto the mass hanger
6.Read and record the new reading of the tape marker from the meter ruler
7.Repeat this method by adding a 100 g mass (at least 5 – 10 times) and record the new scale reading from the metre ruler
define strength
Strength is a measure of the stress that can be applied to a material before it permanently deforms or breaks
ultimate tensile strength
The maximum stress reached before fracture
define tough
The ability to absorb energy and plastically deform without fracture
define ductile
materials that can be stretched or bent without breaking under stress
define brittle
materials that are easily broken, cracked, or snapped when subjected to stress. Brittle materials have little or no plastic deformation
equation for young modulus
young (nm^-2)=Stress(nm^-2)/strain
derived young modulus formula
young= force x original length / area x extension
define young modulus
Young’s modulus is a measure of how stiff a material is when it is stretched or compressed
limit of proportionality
The limit of proportionality is a term that describes the point at which the extension of an elastic object, such as a spring, is no longer directly proportional to the force applied to it. This means that Hooke’s law, which states that force is equal to the spring constant times the extension, is no longer valid beyond this point.
yield point
The yield point is a term that describes the moment when a material stops deforming elastically and instead begins to plastically deform.
what is plastic deformation
Plastic deformation is the process in which an object changes its size or shape in a way that is not reversible because of the applied force
elastic deformation
Elastic deformation is a temporary change in the shape or size of a material that occurs when the applied stress is less than the elastic limit of the material
elastic limit
the elastic limit is the maximum amount of stress that can be applied to a material before the onset of plastic deformation
explain the link between stress, strain and young modulus
Stress is the force per unit area acting on a material. It can be tensile, compressive, or shear, depending on the direction of the force. Strain is the change in length per original length of a material. It can be positive (elongation) or negative (contraction). Young modulus is the ratio of stress and strain for a material in the elastic region. It is a measure of how stiff a material is, or how much it resists deformation.
The relationship between stress and strain is linear for a material in the elastic region, which means that they are directly proportional to each other. This is expressed by Hooke’s law, which states that stress is equal to Young modulus times strain
