Properties Of Matter

Question 1

What is elasticity

Answer 1

It is the ability of a body to return to it’s original state after being distorted by an external force

Question 2

What is stress and the types

Answer 2

Stress is force per unit area.
The types are: normal or tensile stress( using normal force )
And
Shear or tangential stress ( using tangential force)

Question 3

What is strain

Answer 3

It is the change in length per original length

Question 4

What are the two types of strain and how are they caused

Answer 4

• Tensile strain; caused by tensile stress
• Shear strain; caused by shear stress

Question 5

What is elastic modulli

Answer 5

It is the ratio of stress to strain of a material

Question 6

What are the types of elastic modulli

Answer 6

Young modulus = Normal or tensile stress/ tensile strain
Bulk modulus = volume stress( change in pressure or normal stress)/ (change in volume ÷ original volume)
Shear modulus = Tangential or shear stress/ shear/tangential strain

Question 7

What is the value of shear strain

Answer 7

Change in position of a point/ height
It’s also equal to tan theta

Question 8

What formula describes the work done on a string

Answer 8

½Fe = ½ke²

Question 9

What are the possible pickings for a cubic crystal structure

Answer 9

Simple cubic (atoms at the eight corners of the cube)
Face centred cubic (atoms at the eight corners of the cube including one at the centre of each face of the cube)
Body centred cubic ( atoms at the eight corners of the cube including one at the centre of the cube)

Question 10

What are the differences between amorphous and crystalline substances

Answer 10

Crystalline have definite high melting point, their atoms are regularly arranged, they have a definite shape, could be hydrous or anhydrous, they are usually soluble in water and amorphous are the opposite: no definite melting point, atoms are arranged irregularly, are always anhydrous

Question 11

What is buoyant force

Answer 11

It’s the ability of an object to float in a fluid

Question 12

State Archimedes’ principle

Answer 12

It states that when an object is partially or totally immersed in a fluid, it experiences an upthrust which is equal to the weight of the fluid displaced

Question 13

What is surface tension

Answer 13

It is the force per uni length along a direction perpendicular to the surface of the liquid

Question 14

What are the factors that surface tension depend on

Answer 14

Temperature (the higher the temp. the lower the surface tension and vice versa)
The medium at the other side of the liquid surface

Question 15

Mention some surface tension phenomena

Answer 15

Insects walking on water and not getting wet
Needle floating on water surface
Formation of spherical drops

Question 16

What is capillarity

Answer 16

It is the rise or fall of an object in a tube with small radius

Question 17

What is the angle of contact

Answer 17

It is that angle between the tangent to the liquid surface and the solid surface

Question 18

What effect does the angle of contact have on wetting of surfaces

Answer 18

If the angle of contact < 90; the liquid wets the solid surface
If the angle of contact > 90; the liquid does not wet the solid surface

Question 19

What is the difference between the pressure inside and outside of a bubble and a drop

Answer 19

For bubble; 4T/r
For drop; 2T/r

Question 20

What formula describes the viscous force/frictional force in a fluid

Answer 20

F = 6 x pi x coefficient of viscosity x velocity x radius

Question 21

What formula gives the distance risen or fallen by a liquid in a capillary tube

Answer 21

h = 2Tcos(angle of contact)/ prg

Question 22

What is temperature

Answer 22

It is the measure of the average kinetic energy of a body

Question 23

What is heat energy

Answer 23

It is total internal energy of a body

Question 24

What are the types of thermometer

Answer 24

Gas thermometer
Thermocouple
Liquid-in-glass thermometer
Bimetallic thermometer
Resistance thermometer

Question 25

What is fundamental interval of a thermometer

Answer 25

It is the difference between the two fixed points(ice point and steam point)

Question 26

What are the ways of energy transfer

Answer 26

( In order of decreasing speed) Radiation(vacuum), Conduction(the three states of matter), convection(in fluids)

Question 27

What is latent heat

Answer 27

It is the the heat absorbed or evolved during a phase change without a change in temperature

Question 28

What are the types of latent heat

Answer 28

Latent heat of vapourization Latent heat of fusion

Question 29

State the pressure law

Answer 29

It states that at constant volume, the pressure of a given mass gas is directly proportional to the temperature

Question 30

Is absolute zero temperature achievable practically

Answer 30

No

Question 31

What is thermodynamics

Answer 31

It is the branch of physics the deals with the conversion of thermal energy to useful mechanical energy and vice versa

Question 32

Give examples of thermodynamic systems

Answer 32

Heat engine(converts thermal energy into mechanical energy) Refrigerator Steam engine Petrol engine Diesel engine

Question 33

State the first law of thermodynamics

Answer 33

It states that when a system absorbs heat energy(Q) and work(W) is done, there is a change in its internal energy (U) Chang in U = Q - W

Question 34

State the zeroth law of thermodynamics

Answer 34

It states that when are two systems that are at thermal equilibrium individually with a third system , then the two systems are at thermal equilibrium with each other

Question 35

What is entropy and its formula

Answer 35

It is the degree of disorderliness/ randomness in a system. It is the non useful energy in a system S= (change in Q)/T

Question 36

State the second law of thermodynamics

Answer 36

It states that in an isolated system, a process will only take place if the entropy increases or is constant (S _> 0) S= 0 for an irreversible reaction

Question 37

What is a reservoir

Answer 37

It is a sink of infinite heat capacity, it's temperature does not change no matter how much heat is applied

Question 38

State the third law of thermodynamics

Answer 38

It states that the temperature of a system cannot be reduced to the absolute zero by a finite number of steps

Question 39

What are the types of thermal processes involving temperature, pressure and volume

Answer 39

Isobaric/isopiestic : it takes place at constant pressure W = P(V2 -V1) Isochoric/isovolumic: it takes place at constant volume W=P(0) = 0 Change in U = Q Isothermal: takes place at constant temp W = n R T ln(V2/V1) Adiabatic: there is no exchange of heat. Change in U = -W