SOME QUESTIONS ON DIFFERENTIABILITY

• Find the point on the curve y = 2x² – 6x – 4 at which the tangent is parallel to the x – axis
• Find the slope of tangent for y = tan x + sec x at x = π/4
• For the curve y = 3x² + 4x, find the slope of the tangent to the curve at the point x = -2.
• Find a point on the curve y = x² – 4x -32 at which tangent is parallel to x-axis.
• Find a, for which f(x) = a(x+sinx)+a is increasing .
• The side of a square is increasing at 4 cm/minute. At what rate is the area increasing when the side is 8 cm long?
• Find the point on the curve y =x²-7x+12, where the tangent is parallel to x-axis.

C++ program to illustrate passing of structures by value.

Write a C++ program to illustrate passing of structures by value. 

#include<iostream.h>
#include<conio.h>
#include<stdio.h>
struct distance{
 int feet;
 int inches;
};
int main()
{
clrscr();
    distance length1, length2;
void prnsum(distance l1, distance l2);
cout<<"\n"<<"Enter length 1:\n";
cout<<"\n"<<"Feet:\n";
cin>>length1.feet;
cout<<"\n"<<"Inches:\n";
cin>>length1.inches;
cout<<"\n"<<"\n"<<"Enter length 2:\n";
cout<<"\n"<<"Feet:\n";
cin>>length2.feet;
cout<<"\n"<<"Inches\n";
cin>>length2.inches;
prnsum(length1, length2);
return 0;
}
void prnsum(distance  l1, distance l2)
{
  distance l3;
  l3.feet = l1.feet + l2.feet + (l1.inches +l2.inches)/12;
  l3.inches =( l1.inches + l2.inches)%12;
  cout<<"\n"<<"\n";
  cout<<"\n"<<"Total Feet:"<<l3.feet<<"\n";
  cout<<"\n"<<"Total Inches:"<<l3.inches;
  return;
}
/*
OUTPUT
------

Enter length 1:

Feet:
10

Inches:
1

Enter length 2:

Feet:
12

Inches
2

Total Feet:22

Total Inches:3


*/

Real Me Vs Virtual Me?

With recent studies showing that,[1]

• 93% of teens (12-17) go online.

• Of the children (0-5) who use the Internet, 80% use it at least once a week.

• 75% of teens (12-17) have cell phones.

• On average, texting teens (12-17) send and receive 1500 text messages a month. 

• 73% of teens (12-17) have profiles on social networking sites.

Are we starting to leave the 'real me' behind as we run behind the 'virtual me'? 

Why not invite your friends over and have a face to face chat with them?! 
How about a cup of hot chocolate together with friends on a winter evening?!
what do you think about sharing 'likes' and dislikes in person?!

With all due respect to the internet without which, me from my study table wont be able to have you reading my post from probably another side of the globe!

This post is just a reminder to us that, there are other way of socialising other than  texting or chatting or through social networking sites!  

Have fun being the Real-U! :)

Are you stressed out?

Are you stressed out because of exams, school and tests?! 

These tips might help you overcome your stress :) 

1.Have a test tomorrow and haven't touched your books yet?!

•    Step 1: STOP PANICKING! (no point panicking now. We have already committed the mistake)
•    Step 2: Don't waste the time you have in hand RIGHT NOW. 
•    Step 3: Start off immediately and study as much as you can.
•    Step 4: Start the next day afresh and give your test with confidence. 

2.Are all your class lessons going over your head?!

•    Step 1: STOP PANICKING! 
•    Step 2: Dedicate a weekend (or more depending on much you are lagging behind/ how high over your head the lessons are going!) for your studies. Revise all your lessons. 
•    Step 3: Get ready to kick off the next week with the 'new and improved' you!

3. Do you feel overloaded?!

• Make sure you have some 'YOU-time' everyday.
• Don't miss out on doing things you enjoy.
• Pursue your hobbies.
• Remember, its not only studies that matter. 

4. What does your plate have to say about you?!

• Avoid junk food.
• Healthy food => Healthy Body & Healthy Brain. 

5. Cluttered desk = Cluttered mind. 

• Get organized. 
• All it takes is a simple rule ''Put things back to where they belong."
• Collect one-sided papers and reuse them.
• Give away your old school books to your friend who may need it or for charity.
• Discard materials that can no longer be used.

6. Are you getting enough sleep?

• Don't sacrifice your sleep! 
• Make sure you get at least 7 hours of good night's sleep.

GOOD LUCK! 

*results may vary :P

CBSE SAMPLE PAPERS 2012

Click the links below to view.

• Maths
• Physics
• Chemistry
• Biology
• Computer Science

C++ Program

Write a C++ Program to store information of 10 employees and to display information of an 
employee depending upon the employee no.


#include<iostream.h>
#include<conio.h>
#include<stdio.h>
struct addr
{
int houseno;
char area[30];
char city[30];
char state[30];
};
struct emp
{
int empno;
char name[30];
char desig[30];
addr address;
float basic;
}worker;
emp sales_emp[10];
void display(int a);
void enter(void);
int main()
{
clrscr();
int eno,i;
char ch;
enter();
do
{
cout<<"\n Enter the employee no. whose information is to be displayed:";
cin>>eno;
int flag=0;
for(i=0;i<2;i++)
{
if(sales_emp[i].empno==eno)
{
display(i);
flag=1;
break;
}
}
if(!flag)
{
cout<<"\n sorry! no such employee found";
}
cout<<"\n display more...(y/n)\n";
cin>>ch;
}while(ch=='y');
getch();
return 0;
}
void enter(void)
{
for(int i=0;i<2;i++)
{
cout<<"\n employee no:";
cin>>sales_emp[i].empno;
cout<<"\n name:";
gets(sales_emp[i].name);
cout<<"\n designation:";
gets(sales_emp[i].desig);
cout<<"\n * address *";
cout<<"\n house no:";
cin>>sales_emp[i].address.houseno;
cout<<"\n area:";
gets(sales_emp[i].address.area);
cout<<"\n city:";
gets(sales_emp[i].address.city);
cout<<"\n state:";
gets(sales_emp[i].address.state);
cout<<"\n basic pay:";
cin>>sales_emp[i].basic;
cout<<"\n\n";
}
return;
}
void display(int a)
{
cout<<"\n employee data";
cout<<"\n enployee no.:"<<sales_emp[a].empno;
cout<<"\n name:";
cout.write(sales_emp[a].name,30);
cout<<"\n designation:";
cout.write(sales_emp[a].desig,30);
cout<<"\n address:"<<sales_emp[a].address.houseno;
cout<<" \n";
cout.write(sales_emp[a].address.area,30);
cout<<" \n";
cout.write(sales_emp[a].address.city,30);
cout<<" \n";
cout.write(sales_emp[a].address.state,30);
cout<<" \n";
cout<<"\n basic pay:"<<sales_emp[a].basic;
cout<<"\n\n";
return;
}

C++ Program

Write A C++ Program To Read Values Into A Nested Stucture. 


#include<iostream.h>
#include<conio.h>
#include<stdio.h>
struct addr
{
int houseno;
char area[30];
char city[30];
char state[30];
};
struct emp
{
int empno;
char name[26];
char desig[26];
addr address;
float basic;
}worker;
int main()
{
clrscr();
cout<<"\n enter employee no.:\n";
cin>>worker.empno;
cout<<"\n name:\n";
gets(worker.name);
cout<<"\n enter designation:\n";
gets(worker.desig);
cout<<"\n enter address:\n";
cout<<"\n house no.:\n";
cin>>worker.address.houseno;
cout<<"\n area:\n";
gets(worker.address.area);
cout<<"\n city:\n";
gets(worker.address.city);
cout<<"\n basic pay:\n";
cin>>worker.basic;


cout<<"\n ***********\n";
cout<<"\n employee no.:\n ";
cout<<worker.empno;
cout<<"\n name:\n ";
puts(worker.name);
cout<<"\n designation:\n ";
puts(worker.desig);
cout<<"\n :address:\n ";
cout<<"\n house no.:\n ";
cout<<worker.address.houseno;
cout<<"\n area:\n ";
puts(worker.address.area);
cout<<"\n city:\n ";
puts(worker.address.city);
cout<<"\n basic pay:\n ";
cout<<worker.basic;
getch();
return 0;
}

ELECTROSTATICS

ELECTROSTATICS - Frequently asked questions

1. Define the term electric dipole moment. Is it scalar or vector quantity?
2. An electric dipole of dipole moment 20 x 10-6 Cm is enclosed by a closed surface. What is the net flux coming out of the surface?
3. Define the term electric flux. Write its SI unit.
4. An electric dipole of length 10 cm having charges ± 6 x 10-3 C, placed at 300 with respect to a uniform electric field, experiences a torque of 6√3 Nm. Calculate: (1) The magnitude of the electric field.(2) The potential energy of the dipole.
5. A charge q is placed at the centre of the line joining the two equal charges Q Show that the system of three charges will be in equilibrium if q = - Q/4.
6. Two fixed point charges + 4e and + e units are separated by a distance ‘a’. Where should the third point charge be placed for it to be in equilibrium?
7. Two similarly and equally charged identical metal spheres A and B repel each other with a force of 2 x 10-5 N. A third uncharged sphere C is touched with A and then placed at the mid point between A and B. Calculate the net electric force on C.
8. State Gauss’s theorem in electrostatics. A charge of 17.7 x 10-4 C is distributed uniformly over a large sheet of area 200 sqm . Calculate the electric field intensity at a distance 20 cm from it in air.
9. An electric dipole is free to move in a uniform electric field . Explain its motion when it is placed (1) parallel to the field and (2) perpendicular to the field.
10. Two identical metallic spheres ,having unequal, opposite charges are placed at a distance 0.90 m apart in air. After bringing them in contact with each other , they are again placed at the same distance apart. Now the force of repulsion between them is 0.025 N. Calculate the final charge on each of them.
11. Force of attraction between two point charges placed at a distance ‘d’ apart in a medium is F. What should be the distance in the same medium so that the force of attraction between them becomes 9F?
12. Two point charges of + 3 x 10-19 C and + 12 x 10-19 C are separated by a distance of 2.5 m. Find the point on the line joining them at which the electric field intensity is zero.
13. A hollow conducting sphere of radius 8 cm is given a charge 16 µC . What is the electric field intensity?(1) at the centre of the sphere and (2) on the outer surface of the sphere.
14. Two point electric charges of values q and 2q are kept at a distance ‘d’ apart from each other in air. A third charge Q is to be kept along the same line in such a way that the net force acting on q and 2q is zero. Calculate the position of charge Q in terms of q and d.
15. What is electric flux? Write its SI unit.Using Gauss’s theorem , deduce an expression for the electric field at a point due to uniformly charged infinite plane sheet.
16. What is an electric dipole ? Derive an expression for the torque acting on an electric dipole, when held in a uniform electric field. Hence define the dipole moment.
17. Find the value of electric field that would exactly balance the weight of electron.
18. There is a sphere of radius 20 cm.What charge should be given to the sphere so that it acquires a surface charge density of 3/π C/sqm?

*********************************************************************************

Answers coming soon!!!

MATHS: PROBABILITY

A few questions in probability....


Q. 1. Two dice are rolled once. Find the probability that:
1. the numbers on two dice are different
2. the total of numbers on the two dice is at least 4
Q. 2. A pair of dice is tossed twice. If the random variable X is defined as the number of doublets, find the probability distribution of X.


Q. 3. In a factory, which manufactures nuts, machines A, B and C manufacture respectively 25%, 35% and 40% of nuts. Of their output 5, 4 and 2 per cent respectively are defective nuts. A nut is drawn at random from the product and is found to be defective. Find the probability that it is manufactured by machine B.


Q. 4. If the mean and variance of the binomial distribution are respectively 9 and 6, find the distribution.


Q. 5.8% of people in a group are left handed. What is the probability that 2 or more of a random sample of 25 from the group are left handed?

CHEMISTRY: CONVERSIONS

Convert the following:


1. phenol to salicylic acid
2. chlorobenze to phenol
3. ethene to 1,2 ethanediol
4. phenol to salicylaldehyde
5. methyl bromide to acetic acid
6. tolune to benzaldeyde
7. acetic acid to ethylamine
8. bezene to acetophenone
9. ethanol to propanone
10. benzoyl chloride to benzaldehyde
11. acetaldehyde to crotonaldehyde
12. Benzoyl chloride to benzaldehyde.
13. Acetic acid to acetone.
14. Ethyl isocyanide to ethyl amine.
15. Aniline to N-phenyl ethenamide.
16. Propane to 1- bromopropane.
17. 2propanol to lodoform.
18. ethene to ethanol.
19. phenol to phenylethanoate.
20. Ehenol to 2 propanol.
21. Propene to 2- propanone.
22. Aniline to p-Chloro benzene.
23. 2-propanol to 2-propanone.
24. Proponoic acid to 1 propanol
25. Acetophenone to benzoic acid.
26. Aniline to para bromobenzene
27. 2-Butonol from ethanol
28. Benzene to o nitro chlrobenzene
29. Propane from 2 propanol
30. phenol from aniline
31. Benzaldehyde in to acetaphenone
32. Melonic acid in to acetic acid
33. Acetaldehyde in to 2 butenol
34. Glycerol from glyceides
35. 2,4,6 tribromo phenol from phenol
36. Ethanoic acid to propanoic acid
37. Acetic acid to diethyl ammine
38. Nitro benzene to phenol
39. Aniline to benzoic acid
40. Phenol to 2acetoxybenzoic acid
41. benzene in to P chloronitrobenzene
42. Propanoic acid to acetic acid
43. Propanoic anhydride from propanoic acid
44. Ethyl amine to acetic acid
45. Methyl cyanide to acetaldehyde
46. Benzadehyde to cyanobenzene
47. Nitrobenzene to nitrophenol
48. Acetaldehyde into lactic acid