Materials Flashcards
(42 cards)
What is density ?
The mass per unit volume
When will the object float ?
If the density of the object is greater than the fluid
How would you convert from kgm^-3 to gcm^-3 ?
10^3 / 10^6 = 10 ^-3
How would you find the density of regular and irregular objects ?
- using a measuring cylinder and measuring the volume increase or a eureka can
-for regular objects can be found using the mass over volume
How to calculate the density of alloys ?
( Mass x + mass y ) / volume
(Density*volume x ) + (density * volume y ) / volume
What is an elastic material ? C
A material which returns to its original shape after the deforming force is removed
What is an inelastic material ?
An object that doesn’t return to it’s original once the deforming forces are removed
What does hooks law state ?
The extension of a material is directly proportional to the force applied until the limit of proportionality
What is the spring constant ?
A constant value measured in n/m (gradient of a force extension graph )
What does the greater value for k tell us about the force required to produce an extension ?
The greater the value is the greater force is required to produce an extension ( stiffer )
What is the limit of proportionality
The point beyond with force and extension are no longer directly proportional ( hook’s law is not obeyed )
What is the elastic limit ?
The point beyond the which the material is permanently deformed and does not return to its original length
What is the breaking point ?
If the force is increased till a point where the atoms are broken apart (maximum force or stress before the material breaks )
What is the ultimate tensile strength ?
The greatest possible applied force. All deformation beyond here the material would start to neck
What is elastic strain energy ?
The energy stored within the material when it is stretched. Before the material reaches its elastic limit all the energy is stored as elastic strain energy.
How can the work done or elastic strain energy be found using a force- extension graph ?
The area under the graph
What would the force exerted on spring in series be ?
The force exerted would be the same
What would the extension of the two springs in series be ?
The sum of the extensions
How would you work out the total spring constant for spring in series ?
1/kt =1/k1 + 1/ K2 …
What would happen to the extension for springs in parallel ?
It would be the same for each spring
What would the force exerted be for spring in a series circuit ?
The total force would be equal to the sum of the deforming forces exerted on each spring
What is the spring constant for spring in parallel
Kt = k1 +k2 …
What happens to the unloading line when an object passes the elastic limit for a metal wire ?
The unloading line would be parallel to the loading line
From a force extension graph how would you be able to work out the work done to permanently deform the material ?
The area between the loading and unloading lines
