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Append (+ =)

Adding more strings at the end of an existing string is known as append. The operator + = is used to append a new string with an existing string. 

Example:

>>> str1= ’Welcome to ”

>>> str1+= ”Leam Python”

>>> print (str1)

Welcome to Learn Python

The function isalnum( ) returns False when it contains special characters.

When the sun is setting, the light from it has to travel a greaater thickness of the earth’s atmosphere and only longer wavelength red light is able to reach us. Sunset is therefore red

Before writing program.

It checks if the value of left operand is greater than or equal to the value of right operand, if yes then condition becomes true.

It checks if the value of left operand is less than or equal to the value of right operand, if yes then condition becomes true.

No,  there are not equivalent of C’s “?:” ternary operator in Python.

It is an acronym for Indian Standard Code for Information Interchange. It is an 8-bit code so it has 28 = 256 possible code groups. It retains all ASCII characters and offers to code for Indian characters also.

It is the new universal coding standard being adopted for all newer platforms. Unicode provides a unique number for every character, no matter what the platform or program or the language is.

No,”< =” is not assignment operator.

Following example to understand all the identity operators available in Python programming language :

# !/usr/bin/py thon

a = 20 

b = 20

if (a is b): 

print “Line 1 – a and b have same identity” 

else: 

print “Line 1 – a and b do not have same identity” 

if (id(a) = = id(b)): 

print “Line 2 – a and b have same identity” 

else: 

print “Line 2 – a and b do not have same identity” 

b = 30 

if (a is b ): 

print “Line 3 – a and b have same identity” 

else: 

print “Line 3 – a and b do not have same identity”

if (a is not b ): 

print “Line 4 – a and b do not have same identity” 

else:

print “Line 4 – a and b have same identity”

When you execute the above program it produces following result:

Line 1 – a and b have same identity 

Line 2 – a and b have same identity 

Line 3 – a and b do not have same identity 

Line 4 – a and b do not have same identity

Following example to understand all the assignment operators available in Python programming language : 

# !/usr/bin/python 

a = 21 

b = 10 

c = 0 

c = a + b 

print “Line 1 – Value of c is “, c 

c += a 

print “Line 2 – Value of c is “, c 

c *= a 

print “Line 3 – Value of c is “, c 

c/= a 

print “Line 4 – Value of c is “, c 

c = 2 

c %= a 

print “Line 5 – Value of c is “, e 

c**= a 

print “Line 6 – Value of c is “, c

 c//= a 

print “Line 7 – Value of c is “, c 

When you execute the above program it produces following result: 

Line 1 – Value of c is 31 

Line 2 – Value of c is 52 

Line 3 – Value of c is 1092 

Line 4 – Value of c is 52 

Line 5 – Value of c is 2 

Line 6 – Value of c is 2097152 

Line 7 – Value of c is 99864

Following example to understand all the bitwise operators available in Python programming language:

# !/usr/bin/python

a = 60 # 60 = 0011 1100 

b = 13 # 13 = 0000 1101 

c = 0

c = a & b; # 12 = 0000 1100 

print “Line 1 – Value of c is “, c

c = a | b; # 61 = 0011 1101 

print “Line 2 – Value of c is “, c

c = a ∧ b; # 49 = 0011 0001 

print “Line 3 – Value of c is “, c

c = ~a; # -61 = 1100 0011 

print “Line 4 – Value of c is “, c

c = a < < 2; #240 = 1111 0000 

print “Line 5 – Value of c is “, c

c = a > > 2; # 15 = 00001111 

print “Line 6 – Value of c is “, c

When you execute the above program it produces following result:

Line 1 – Value of c is 12 

Line 2 – Value of c is 61 

Line 3 – Value of c is 49 

Line 4 – Value of c is -61 

Line 5 – Value of c is 240 

Line 6 – Value of c is 15

It is an acronym for the American Standard Code for Information Interchange. It is used in most microcomputers and minicomputers and in many mainframes. It is a 7-bit code so it has 27 = 128 possible code groups.

Print “These are the values a, b, c. 

These are the values : 9300.0.

Following example to understand all the membership operators available in Python programming language :

#!/usr/bin/python 

a = 10 

b = 20 

list = [1,2,3,4, 5 ];

if ( a in list): 

print “Line 1 – a is available in the given list” 

else:

 print “Line 1 – a is not available in the given list”

if (b not in list): 

print “Line 2 – b is not available in the given list”

 else: 

print “Line 2 – b is available in the given list”

a = 2 

if ( a in list): 

print “Line 3 – a is available in the given list” 

else:

 print “Line 3 – a is not available in the given list”

When you execute the above program it produces following result:

Line 1 – a is not available in the given list 

Line 2 – b is not available in the given list 

Line 3 – a is available in the given list

Answer is (b) perpendicular to each other

Following example to understand all the comparison operators available in Python programming language:

# !/usr/bin/python 

a = 21 

b = 10 

c = 0 

if (a = = b ): 

print “Line 1 – a is equal to b” 

else: 

print “Line 1 – a is not equal to b” 

if ( a ! = b ): 

print “Line 2 – a is not equal to b” 

else: 

print “Line 2 – a is equal to b” 

if (a <> b): 

print “Line 3 – a is not equal to b” 

else: 

print “Line 3 – a is equal to b”

if ( a < b ): 

print “Line 4 – a is less than b” 

else: 

print “Line 4 – a is not less than b” 

if (a > b ): 

print “Line 5 – a is greater than b” 

else: 

print “Line 5 – a is not greater than b” 

a = 5; 

b = 20; 

if (a < = b): 

print “Line 6 – a is either less than or equal to b” 

else: 

print “Line 6 – a is neither less than nor equal to b”

 if (b > = a): 

print “Line 7 – b is either greater than or equal to b”

 else: 

print “Line 7 – b is neither greater than nor equal to b” 

When you execute the above program it produces following result: 

Line  1 – a is not equal to b 

Line  2 – a is not equal to b 

Line  3 – a is not equal to b 

Line  4 – a is not less than b 

Line  5 – a is greater than b 

Line  6 – a is either less than or equal to b 

Line  7 – b is either greater than or equal to b

Following example to understand all the arithmetic operators available in Python programming language: 

# !/usr/bin/python 

a = 21 

b = 10

 c = 0 

c = a + b 

print “Line 1 – Value of c is “, c 

c = a -b 

print “Line 2 – Value of c is “, c 

c = a * b 

print “Line 3 – Value of c is “, c 

c = a/b 

print “Line 4 – Value of c is “, c 

c = a % b 

print “Line 5 – Value of c is “, c 

a = 2 

b = 3 

c = a**b 

print “Line 6 – Value of c is “, c 

a = 10 

b = 5 

c = a//b 

print “Line 7 – Value of c is “, c 

When you execute the above program it produces following result: 

Line 1 – Value of c is 31 

Line 2 – Value of c is 11 

Line 3 – Value of c is 210 

Line 4 – Value of c is 2 

Line 5 – Value of c is 1 

Line 6 – Value of c is 8 

Line 7 – Value of c is 2

Answer is (b) perpendicular

Relation R is defined as

R = {(x,y) : x, y \(\in\) N and x divides y}

Reflexive:

Let x \(\in\) N and every natural number divides itself.

\(\therefore\) x divides x.

⇒ x R x \(\forall\) x \(\in\) N

\(\therefore\) Relation R is reflexive relation.

Symmetric: \(\because\) 2 divides 6

i.e., (2, 6) \(\in\) R

But 6 does not divide 2

\(\because\) (6, 2) \(\notin\) R

Hence, relation R is not symmetric.

Transitive:

Let x R y, x R z

i.e., x divides y & y divides z.

Let y = ax & z = by where a & b are arbitary constant such that x divides y & y divides z.

⇒ z = by = b(ax)

= ab x

\(\therefore\) x divides z.

⇒ x R z.

So, R is transitive relation.

For reflexive 

x divides x i.e., x Rx, ∀ x ∈ N

R is reflexive

For symmetric

2 divides 6 2R6 i.e., (2,6) ∈ R but (6,2) ∈! R as 6 does not divide 2

Also, R is not symmetric

For transitive 

Let x divides y and y divides z 

i.e., xRy and yRz

kj₁x = y & k₂y = z (k₁,k₂ are positive integer)

k₁k₂x = k₁y = z

x divides z 

xRz

So, R is transitive.

We have vector a = 4i + 3j + 2k

2 vector a = 8i + 6j + 4k and vector b = 3i + 2k

= 3i + 0j + 2k

∴ vector|b x 2a| = |(i,j,k),(3,0,2),(8,6,4)|

= i(0 - 12) - j(12 - 16) + k(18 - 0)

= -12i + 4j + 18k

∴ vector|b x 2a| = √(12² + 4² + 18²) = √484 = 2√121

= 22

Answer is (c) [(0,0),(0,0)]

Putting x = tan θ, we get

y = cos^-1 (1 - tan² θ)/(1 + tan² θ) = cos^-1 cos 2 θ = 2θ = 2tan^-1 x

∴ dy/dx = 2 x 1/(1 + x²) = 2/(1 + x²)

y = e^x(sin x + cos x)

Differentiating w.r.t x, we get

dy/dx = e^x(d(sin x + cos x)/dx)

= e^x(cos x - sin x)

Again differentiating w.r.t x, we get

d²y/dx² = -e^x(sin x - cos x)

d²y/dx² = -2(dy/dx) + 2y = 0

Given, x cos y = sin(x + y)

Differentiating both sides w.r.t. 'x', we get

x(-sin y).(dy/dx) + cos y = cos(x + y)[1 + (dy/dx)]

-x sin y.(dy/dx) + cos y = cos(x + y) + cos(x + y).(dy/dx)

(dy/dx)[cos(x + y) + x sin y] = cos y - cos(x + y)

∴ dy/dx = (cos y - cos(x + y))/(cos(x + y) + x sin y)

When the change in momentum is a constant, the force acting on a body will be inversely proportional to the time taken. As time increase, the force acting decreases and as time decreases, the force acting increases.

From the graph

Initial velocity u = 20 m/s

Final velocity v = 0m/s

t = 10 s

m = 20

g = 20/100 kg

F = ma

= \(m\frac{(\text{v}-\text{u})}{t}\)

= \(\frac{20}{1000}\times\frac{(0-20)}{10}\)

= -0.04 N

The negative sign shows that the frictional force is acting opposite to the direction of motion of the object.

When the change in momentum is a constant, the force acting on a body will be inversely proportional to the time taken. As time increase, the force acting decreases and as time decreases, the force acting increases.

Loaded vehicles possess more inertia of motion. As ” mass increases, inertia also increases.

(a) This activity helps to cover long distances by utilizing inertia of motion.

(b) Mass of elephant is greater. So inertia of motion also be greater. Also, it cannot be able to change its direction suddenly.

D) regions close to the equator

B) Growing more trees

Correct option is C) Climate

One should treat Shakespeare, Raphael and Beethoven important because they have produced beautiful plays, pictures and music which are helpful in civilization.

Joad thinks that Caliphs and Princes in the Arabian Nights were not civilized because they passed only a luxurious life and did not think new things freely.

No, the use of machines, trains, wireless, etc. do not make us civilized because there is nothing to be proud of in having them

According to Lucy wearing proper clothes, riding in buses and cars and having money to buy things make one civilized.

Context : In this lesson the author explains the meaning of civilization through a dialogue between himself and a little girl Lucy. He says that in the olden times the priests misguided the people. They asked them to think and to do as they advised them. If they thought or did contrary to them, the gods would be angry. 

Explanation : In these lines the author explains that thinking freely means thinking differently. But the advice of the priests and the fear of anger of gods prevent a man to think freely. So, for many ages the people followed the priests blindly and did nothing different to their thinking. Hence, there had been no civilization. This type of philosophy checked the way of progress and we could not become civilized.

Heavy metals are Lead and Mercury.

Context : In this lesson the author throws light on some of the factors which are necessary for civilization, e.g. free thinking, security, etc. In the olden days the people were not allowed to think freely. They believed in priests and did what they asked them to do. They were afraid of the anger of gods if they thought differently. So, there could have been no civilization. 

Explanation : In these lines the author describes another factor security which is also very necessary for civilization. If anybody is afraid of being robbed or murdered, he cannot think freely. Besides this, for thinking freely we must have leisure. If we are busy every time in earning money for food, clothes and house, we shall have no free time and we shall not be able to think new things and to talk to other people. Besides this we should have security of our life and property. Thus civilization consists in having free time, security and society.

Context : In this lesson the author explains the meaning of civilization through a dialogue between himself and a little girl Lucy. He concludes that security, leisure and society-all these three things are necessary to free thinking as well as to civilization. 

Explanation : In these lines the author lays emphasis on peace and security which are the most necessary conditions of civilization. If we go on quarrelling with each other, we shall have no time to think or invent new things. In an atmosphere of fear and insecurity, there is always risk to our life. We shall not be able to progress and prosper.

Two sources of water pollution are :

• household detergents and sewage,
• oil spills

Natural sources are volcanic eruptions, sand, dust, forest fires etc.

Context: In this lesson the author explains the meaning of civilization through a dialogue between himself and a little girl Lucy. He comes to the conclusion that security, leisure and society-all these three things are necessary to free thinking as well as to civilization. In an atmosphere of fear and insecurity, there is always risk to our life and we shall not be able to make progress. 

Explanation : In these lines the author makes it clear that civilization is a very wide term. Only to have the rules and to follow them does not make a man civilized. Civilization means to be good. If we want to be good or civilized, we should behave our neighbours in a good manner, we should respect his property and we should follow the rules sincerely. So, all these things make us civilized.

These are Carbon dioxide, Sulphur dioxide, Nitrogen oxides.

Smog means smoke + fog. In winter season smog is responsible for many accidents due to the obstacle in visibility.

When fossil fuels are burnt they cause air pollution. Greenhouse gases are formed and acid rain may also fall.

The wood is one of the most important resources, as it provides timber for houses, construction, fuel for household and industrial purposes, transport lines, agricultural implements, furniture, sports goods, stationery and various consumer goods.