Units, Dimensions, Measurements and Error Analysis - Notes on Physical Quantities - fundamental or basic, derived, supplementary quantities

Hi Friends,
You may be aware that this chapter ‘Units, Dimensions, Measurements and Error Analysis’ though sounds preliminary, is not only important but has direct implications with all other chapters of Physics. Moreover, you will have at least some questions from this chapter whether in NEET, IIT JEE Main or JEE Advanced, AIPMT or in any other Medical and Engineering Entrance Exams or NTSE, KVPY etc.
Section wise notes (part-by-part from this & other chapters) containing important study materials (Tables, Formulae, etc.) have been/will be published in sequence.

Additionally, you have -
Also, scroll below to find a common syllabus for this chapter given at the end.    

Physics and Physical World

The word 'Science' has come from a Lain word, 'Scientica' which means, 'to know'. Science is the subject of knowledge achieved by systematic approach through observation and experience, aimed at understanding natural phenomena in as much detail as possible.
A scientific approach (method) involves various interconnected steps -
1.     Systematic Observation
2.     Controlled Experiment: A controlled experiment involves setting up two experimental conditions that are exactly same except for a single factor that the scientist manipulates.
3.     Rationalisation or Qualitative and Quantitative Reasoning
4.     Mathematical Modelling
5.     Interpretation: Statement based on above observations and some scientific theory. It can be scientifically altered (falsifiable).
6.     Verification or Falsification
Physics is one of the many disciplines of science originated from a Greek word ‘Fusis’, which means ‘nature’.
The two main thrusts in Physics are -
1.     Unification: that is explaining diverse physical phenomena in terms of concepts and laws. For example, the same law of gravitation discovered by Newton also explains planetary motion, motion of moons around a planet as well as a body falling on the earth.
2.     Reduction: It is deriving the properties of a bigger or more complex system from the properties and interaction of its constituent parts. For example, in thermodynamics the temperature is related to the average kinetic energy of molecules of the system.
The two main domains of interest in Physics are -
1.     Macroscopic Domain: This includes Classical Physics which is study of objects of finite size that can be in a laboratory, in a terrestrial scale or even on astronomical scale. For example, mechanics, optics, electrodynamics and thermodynamics.
2.     Microscopic Domain: It includes studies involving atomic, molecular and nuclear phenomena, also interaction of elementary particles like electron, protons.  
Scientific Principle
Steam / Diesel / Petrol Engines:
Laws of Thermodynamics
Laws of Thermodynamics
Bernoulli’s Principle in Fluid Dynamics
Radio & Television:
Principle of Communication Systems using Electromagnetic Waves
Rocket Propulsion:
Newton’s Laws of Motion
Digital Logic
Orbital Motion of Satellites:
Kepler’s Laws of Planetary Motion
Electron Microscope:
Wave Nature of Matter
Electromagnetic Force on Charged Particles
Nuclear Reactor:
Nuclear Fission
Electric Generator, Transformer:
Faraday’s Law of Electromagnetic Induction
Reflection of Ultrasonic Waves
Pressure Cooker
Rising of Boiling Point of water by increasing pressure
Photoelectric Effect
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Physical Quantities

1.     Those quantities which can be measured by an instrument and by which we can describe the laws of physics are called physical quantities. For example - mass, length, time, velocity, force, density etc.
2.     Measurement is necessary to determine magnitude of a physical quantity so that we can compare two similar physical quantities and also prove physical laws or equations.
3.     A Physical Quantity is completely specified if, it has -
·  Numerical value only (ratio): e.g. refractive index, dielectric constant etc.
·  Magnitude only (scalar): e.g. mass, electric charge etc.
·  Magnitude & Direction (vector): e.g. displacement, torque etc.
4.     There are a few physical quantities which are not specified even by unit, magnitude or direction. Such physical quantities are known as Tensors for example, Moment of Inertia, Stress, Strain, Thermal Conductivity, Magnetic Susceptibility and Electrical Permittivity, etc.
5.     Physical Quantity = Numerical Value (n) x Unit (u). Since the Physical Quantity will be a definite or constant value so, if the unit(u) changes, the magnitude(n) will also change but product 'nu' will remain same. That means magnitude of a physical quantity and units are inversely proportional to each other. Larger the unit, smaller will be the magnitude.
6.     There are three types of Physical Quantities: (a) Fundamental or Basic Quantities. (b) Derived Quantities. (c) Supplementary Quantities.

Fundamental (Basic) Quantities:
There are a large number of physical quantities out of which only a few are elementary quantities. We define them as fundamental or basic quantities which are independent of all other quantities and cover the entire span of physics. All other quantities can be derived or expressed in terms of the fundamental quantities by multiplication or division. Fundamental quantities are total 7 in numbers: Length (L), Time (T), Mass (M), Temperature (K), Electric current (A), Luminous intensity (Cd), Amount of substance (mol).

Derived Quantities:
Physical quantities which can be derived from or expressed in terms of basic quantities are called derived quantities. For example - Momentum, Speed etc.

Supplementary Quantities:
Apart from 7 fundamental quantities, there are 2 supplementary quantities:
1.     Plane angle (It is angle between two lines or the angle subtended by an arc of a circle at its center. Its SI unit is ‘Radian’).   
2.     Solid angle (Angle subtended by a given surface area of a spherical surface at its centre is called a solid angle. Its SI unit is ‘Steradian’).
Need for measurement of physical quantities, Units for measurement and Dimensions, System of Units - SI, Fundamental and Derived Units. Dimensional Formula and Dimensional Equations. Dimensional Analysis and its Applications. Significant figures and rounding off the numbers. Measurement of length, mass, and time. Accuracy, Precision of Instruments and error analysis. 

                  Units, Measurements >>

Units, Dimensions, Measurements and Error Analysis - Solved Test Series, Practice Questions

Physics objective questions, Test Series 4 with solutions - Newton’s Laws of Motion and Friction

Below is another set of 10 MCQ practice questions (Q.No.31 - 40) with hints & solutions (link given at the end) from the Physics chapter -Newton’s Laws of Motion and Friction. Physics test series, questions asked in NEET, JEE Main, Medical and Engineering Entrance Exams
Questions from some of these topics (randomly selected):
Force and Inertia; Law of Inertia; Newton’s First Law of Motion; Center of Mass; Momentum; Newton’s Second Law of Motion; Impulse; Newton’s Third Law of Motion; Law of Conservation of Linear Momentum and its applications; Variable Mass; Free Body Diagrams; Pulleys; Equilibrium of Concurrent Forces; Constraint Equations; Pseudo Force; Static and Kinetic Friction; Laws of Friction; Rolling Friction; Centripetal Force and its applications; Impulse; Collision

Newton’s Laws of Motion and Friction

India Study Solution MCQ Test Series – Set 4 (Q. No 31-40)

Question 31: When a constant force is applied to a body, it moves with uniform:
a. Acceleration
b. Velocity
c. Speed
d. Momentum

Question 32: A box ‘A’ is lying on the horizontal floor of the compartment of a train running along horizontal rails from left to right. At time ‘t’, it decelerates. Then the reaction R by the floor on the box is given best by:

Physics MCQ Test Series 4 Question No 32 with solution - Newton’s Laws of Motion and Friction
Question 33: A lift of mass 1000 kg is moving upwards with an acceleration of 1m/s2. The tension developed in the string, which is connected to lift? (g = 9.8m/s2)
a. 9800 N
b. 10800 N
c. 11000 N
d. 10000 N

Question 34: A body of mass 1 kg rests on a smooth surface. Another body B of mass 0.2 kg is placed over A as shown. The coefficient of static friction between A and B is 0.15. B will being to slide on A if a pulled with a force greater than –
Newton’s Laws of Motion and Friction - India Study Solution Test Series 4 Question No 34 image

Question 35: If the coefficient of friction of a plane inclined at 300 is 0.4, then the acceleration of the body sliding freely on it, is: (g = 9.8m/s2)
a. 1. 51 m/s2
b. 3. 54 m/s2
c. 9.8 m/s2
d. 4.9 m/s2

Question 36: A marble block of mass 2 kg lying on ice when given a velocity of 6m/s is stopped by friction in 10 s. Then, the coefficient off friction is:
a. 0.02
b. 0.03
c. 0.06
d. 0.01

Question 37: A block is moving up an inclined plane of inclination θ = 300 with a velocity 5 m/s. If it stops after 0.5 s then what is the value of coefficient of friction (µ) ?
Newton’s Laws of Motion and Friction - India Study Solution Test Series 4 Question No 37 - image

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Question 38: A man getting down a running bus, fails forward because –
a. Due to inertia of rest, road is left behind and man reaches forward
b. Due to inertia of motion upper part of body continues to be in motion in forward direction while feet come to rest as soon as they touch the road
c. He leans forward as a matter of habit
d. Of the combined effect of all the three factors stated in a, b and c

Question 39: A dynamometer D, is connected with two bodies of mass M = 6 kg and m = 4 kg. If two forces F = 20 N and F = 10 N are applied on masses according to figure then reading of the dynamometer will be –
a. 10 N
b. 20 N
c. 6 N
d. 14 N

Question 40: Two masses M1 and M2 connected by means of a string which is made to pass over light, smooth pulley are in equilibrium on a fixed smooth wedge as shown in figure. If θ = 600 and α = 300, the ratio of M1 to M2 is –

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Biology Guide for NEET, MBBS admission tests: Breathing and Respiration, Exchange of Gases - very long answer questions

HUMAN PHYSIOLOGY (Breathing and Respiration, Exchange of Gases)

Biology (Zoology) Very Long Answer Theoretical Questions - TQ5 (Q. No.72-75)
Solved Very Long Answer Biology Questions (Zoology)
Question 72:  How does the exchange of gases occur in respiration between blood and alveolar air?
Answer 72: The exchange of gases (i.e., oxygen and carbon dioxide) between lung alveoli and pulmonary capillaries is called external respiration. It occurs as follows:
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The wall of the alveoli is very thin and has rich network of blood capillaries. Due to this, the alveolar wall seems to be a sheet of flowing blood and is called respiratory membrane. The respiratory membrane consists mainly of (a) alveolar epithelium, (b) epithelial basement membrane, (c) a thin interstitial space (d) capillary basement membrane and (e) capillary endothelium. All these layers form a membrane of 0.2 mm thickness. The respiratory membrane has a limit of gaseous exchange between alveoli and pulmonary blood. It is called diffusing capacity. The diffusing capacity is defined as the volume of gas, that diffuses through the membrane per minute for a pressure difference of 1 mm Hg. It is further dependent on the solubility of the discussing gases. In other words, at the particular pressure difference, the diffusion of carbon dioxide is 20 times faster than oxygen and that of oxygen is two times faster than nitrogen. The partial pressure of oxygen (PO2) in the alveoli is higher (104 mm Hg) than that in the deoxygenated blood in the capillaries of the pulmonary arteries (95 mm Hg). As the gases diffuse from a higher to a lower concentration, the movement of oxygen us from the alveoli to the blood. The reverse is the case in relation to carbon dioxide.
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The partial pressure of carbon dioxide (PCO2)  is higher in deoxygenated blood (45 mm Hg) than in alveoli (40 mm Hg), therefore, carbon dioxide passes from the blood to the alveoli. The partial pressure of nitrogen (PN2) is the same (537 mm Hg) in the alveoli as it is in the blood. This condition is maintained because nitrogen as a gas is not used up by the body.
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Question: 73: Discuss the transport of gases (O2 and CO2) in the blood.
Answer 73: Transport of Oxygen in the Blood: Blood carries oxygen from the lungs to the heart and from the heart to various body parts. Oxygen is transported in the following manners:
1. As dissolved gas: About 3% of oxygen in the blood is dissolved in the plasma which carries oxygen to the body cells.
2. As oxyhaemoglbin: About 97% of oxygen is carried in combination with haemoglobin of the erythrocytes. Haemoglobin (Hb) consists of a protein called globin and a pigment portion called heme. The heme portion contains four atoms of iron, each capable of combining with a molecule of oxygen. Oxygen and haemoglobin combine in an easily reversible reaction to form oxyhaemogloin (HbO2).       Hb + 4O2         Hb (O2)4
Under the high partial pressure, oxygen easily binds with haemoglobin in the pulmonary (lung) blood capillaries. When this oxygenated blood reaches the different tissues, the partial pressure of oxygen declines and the bonds holding oxygen to haemoglobin become unstable. As a result, oxygen is released from the blood capillaries.
Oxygen-haemoglobin Dissociation Curve: The amount of oxygen that can bind with haemoglobin is determined by oxygen tension. This is expressed as partial pressure of oxygen (PO2). The percentage of haemoglobin that is bound with O2 is called percentage saturation of haemoglobin. The relationship between the partial pressure of oxygen (PO2) and percentage saturation of the haemoglobin with oxygen (O2) is graphically illustrated by a curve called oxygen-haemoglobin dissociation curve (also called oxygen dissociation curve).Under normal conditions, the oxygen-haemoglobin dissociation curve is sigmoid shaped or "S" shaped.
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Factors affecting oxygen-haemoglobin dissociation curve: It is shifted either to left or right by various factors-
1. Shift to Right: Shift to right indicates dissociation of oxygen from haemoglobin.
2. Shift to Left: Shift to left indicates acceptance (association) of oxygen by haemoglobin.
3. Bohr Effect: Shifting of the oxygen haemoglobin dissociation curve to the right by increasing carbon dioxide partial pressure is known as Bohr Effect.
Transport of carbon dioxide: In the oxidation of food, carbon dioxide, water and energy are produced. Carbon dioxide in gaseous form diffuses out of the cells into the capillaries, where it is transported in  three ways-
(a). Through blood plasma: Carbon dioxide is transported through this medium in a very little quantity. CO2 combines with water of plasma in presence of carbonic anhydrase enzyme to form carbonic acid.
This soon dissociate into H+ and HCO3-ions. Very little % of CO2 is transported through this method as increased production of carbonic acid increases pH from 7.4 - 4.0.
CO2 + H2O <------> H2CO3  <-----> H+ + HCO3-
(b). By haemoglobin: CO2 combines with haemoglobin to form carbaminohaemoglobin.
Hb + CO2 <-----> HbCO2 
About 30% of CO2  is transported by above 2 methods.
(c). As bicarbonates: About 70% of CO2 is transported   as bicarbonates. Initially, in the RBC potassium haemoglobin dissociates  into K+ + Hb.CO2 when diffuses in the RBC  combines with water of the cytoplasm to form carbonic acid which dissociates into H+ and HCO3-ions. Haemoglobin combine with H+ ions to form haemoglobin acid. While in the plasma same CO2 combines worth water of the plasma to form carbonic acid which forms H+ and HCO3-ions. NaCl dissociates into Na+ + Cl-.
Also Read
Question: 74: Describe how the contraction and relaxation of some skeletal muscles produce respiratory movements.
Answer 74: During exercise forceful expiration take place in which with relaxation inspiratory muscles, contraction of expiratory or respiratory muscles takes place. These muscles are of two place:
1. Abdominal muscles
When abdominal muscles contract, visceral organs of abdominal cavity push diaphragm upwards. So, it become more dome shape. When IICM contract ribs and sternum shift downward and inward. By contraction in both muscles volume of thoracic cavity decrease more and intrapulmonary pressure increase more, so, more expiration occur through respiratory tract called forceful expiration.
Question: 75: Write in detail about various respiratory disorders.
Answer 75: Various respiratory disorders are as follows-
Bronchial Asthma: It is an allergy caused by some allergens like pollen grain, dust particle. Allergen stimulate mast cells to produce histamine that causes contraction of smooth muscles of bronchi. Symptoms-coughing, difficulty in breathing mainly during expiration, breathing with wheezing sound, excess mucus secretion from respiratory tract that may clog bronchi and bronchiole.
Emphysema: Emphysema is an abnormal distension of bronchi, bronchiole and alveolar sac of the lungs mainly due to cigarette smoking. Tifr sepia between alveoli are dissolves and elastic tissue replaced by fibrous connective tissue so that lung become non-elastic. Respiratory surface of lung reduced, bronchiole become non-elastic, alveoli remain filled with air even after exhalation.
Bronchitis: Inflammation of the bronchi due to cigarette smoking, air pollutant like CO and Microbial infection.
Pneumonia: It is an acute infection and inflammation of the lung alveoli by S.pneumonae, Mycoplasma, and some false yeast. Infant, young ones, HIV patient are more sensitive for pneumonia. Symptoms- The alveoli becomes acutely inflammated, most of the air space filled with mucus and fluid with WBC.
Occupational lung diseases: These disorders are caused due to exposure of potentially harmful substances, such as gas, fumes or dusts, present in the environment where a person works.
(a). Silicosis and asbestosis: These are common examples, which occur due to chronic exposure of silica and asbestos dust in the mining industry.
(b). Pneumoconiosis: It is found in coal workers.
(c). Byssinosis: It is found in workers of cotton industry.
 Breathing and Respiration, Exchange of Gases More Practice Questions    

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