Sunday, May 28, 2017
Uniform circular motion
If the particle moves in the circle with a uniform speed, we call it a uniform circular motion. In this case, dv/dt = 0 and equation gives
.
.
Thus, the acceleration of the particle is in the direction of
, that is, towards the centre. The magnitude of the acceleration is α = ω²r.

Thus, if a particle moves in a circle of radius r with a constant speed v, its acceleration is v²/r directed towards the centre. This acceleration is called centripetal acceleration. Note that the speed remains constant, the direction continuously changes and hence the “velocity” changes and there is an acceleration during the motion.
, that is, towards the centre. The magnitude of the acceleration is α = ω²r.
Thus, if a particle moves in a circle of radius r with a constant speed v, its acceleration is v²/r directed towards the centre. This acceleration is called centripetal acceleration. Note that the speed remains constant, the direction continuously changes and hence the “velocity” changes and there is an acceleration during the motion.

The linear acceleration is
.
.
This acceleration is directed towards the centre of the circle.
Non uniform circular motion:
If the speed of the particle moving in a circle is not constant, the acceleration has both the radial and the tangential components. According to equation, the radial and the tangential acceleration are 

Thus, the component of the acceleration towards the centre is ω²r = - v²/r and the component along the tangent (along the direction of motion) is dv/dt. The magnitude of the acceleration is
.
.
The direction of this resultant acceleration makes an angle α with the radius where
.
.Saturday, May 27, 2017
Puzzle 6 [With Answers]

Puzzle 1: Pick
the odd one out:
Crabcake, Laughing, Calmness, Canopy, Stupid, Hijack, First,
Deft, Happy
Answer: Happy
Explanation: All the words except
"happy" contain three consecutive letters of the alphabet.
Crabcake, Laughing, Calmness, Canopy, Stupid, Hijack, First,
Deft
Puzzle 2: Fill
in the missing pair:
BF CH ?
HO LT
Answer: EK
Puzzle 3: If BDG is equal to CFJ, then find the
value of EGJ
Answer: FIM
Puzzle 4: Fill in the sequence:
5 6 9
15 ? 40
Answer: 25
Puzzle 5: Fill
in the blanks:
3 3 5
4 4 ? 5
Answer: 3
Explanation: Number of letters in one, two, three,
four, five, six, seven and so on.
Ordinary D.F equations, their order and degree
Differential equation: An equation containing an independent variable, dependent variable and differential coefficient of dependent variable with respect to independent variable is called a differential equation.

Order of a differential equation: The order of a differential Equation is the order of the highest order derivative
appearing in the equation.
For
example, in the equation
, the order of highest order derivative is 2. So. It is a differential equation of order 2.
, the order of highest order derivative is 2. So. It is a differential equation of order 2.
The equation
is of the order 32, It is a differential equation of order 2.
is of the order 32, It is a differential equation of order 2.
Degree of a differential equation: The degree of a differential equation is the degree of the highest order derivative, when differential coefficient are made free from radicals and fractions.
Example I: Consider the differential equation

In this equation the number of highest order derivative is 2. So it is a differential equation of degree 1.
Example II: Consider the differential equation

In this equation, the order of the highest order derivative is 3. And its power its power is 2. So it is a differential equation of order 3 and degree 2.
Friday, May 26, 2017
Puzzles 6

Puzzle 1: Pick the odd one out:
Crabcake, Laughing, Calmness, Canopy, Stupid, Hijack, First,
Deft, Happy
Puzzle 2: Fill in the
missing pair:
BF CH ?
HO LT
Puzzle 3: If BDG is equal to CFJ, then find the
value of EGJ
Puzzle 4: Fill in the sequence:
5 6 9
15 ? 40
Puzzle 5: Fill in the
blanks:
3 3 5
4 4 ? 5
Nucleic Acids
Definition:
⇒ The
particles in nucleus of a cell, responsible for heredity, are called
chromosomes which are made up of proteins and nucleic acids.
⇒ Nucleic
acids are long chain polymers of nucleotides, so they are also called
polynucleotides.
⇒ Examples:
Deoxyribonucleic acid (DNA) & Ribonucleic acid (RNA).
Chemical Composition of Nucleic Acids:
⇒ Each nucleotide has three components: a 5 - carbon sugar, a phosphate group, and a nitrogenous
base.
⇒ In
DNA molecules, the sugar moiety is β - D - 2 - deoxyribose where as in RNA
molecule, it is β - D - ribose.

⇒ DNA
contains four bases viz. adenine (A), guanine (G), cytosine (C) and thymine
(T).
⇒ RNA
also contains four bases, the first three bases are same as in DNA but the fourth
one is uracil (U).
Structure of Nucleic Acids:
⇒ A
unit formed by the attachment of base to 1’ position of sugar is known as
nucleoside, the sugar carbons are numbered as 1’, 2’, 3’, etc. in order to
distinguish these from bases. When nucleoside is linked to phosphoric acid at
5’ - position of sugar moiety we get a nucleotide.

⇒ Nucleotides
are joined together by phosphodiester linkage between 5’ and 3’ carbon atoms of
pentose sugar.

⇒ A
simplified version of nucleic acid chain is as shown below.

⇒ Information
regarding the sequence of nucleotides in the chain of nucleic acid is called
primary structure. Nucleic acids have a secondary structure also.
⇒ James
Watson and Francis Crick gave a double strand helix structure for DNA. Two
nucleic acid chains are wound about each other and held together by hydrogen
bond between pairs of bases.
⇒ These
are complementary to each other because the hydrogen bonds are formed between
specific pairs of bases.

DNA Fingerprinting:
⇒ Every
individual has unique fingerprints.
⇒ A
sequence of bases on DNA is also unique for a person and information regarding
this is called DNA fingerprinting.
⇒ It
is same for every cell and cannot be altered by any known treatment.
Uses of DNA finger printing:
i)
In forensic laboratories for identification of criminals.
ii)
To determine paternity of individual
iii)
To identify racial groups to rewrite biological evolution.
Biological functions of Nucleic acids:
⇒ DNA
is the chemical basis of heredity and may be regarded as the reserve of genetic
information.
⇒ DNA
is responsible for maintaining the identity of different species of organisms
over millions of years.
⇒ A
DNA is capable of self-duplications during cell division and identical DNA
strands are transferred to daughter cells.
⇒ Nucleic
acids are responsible for protein synthesis in the cell.
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