ECAT and MCAT Preparation: Post your doubts here!

[smzimran]

AoA,
Many of us will be preparing for ECAT and MCAT for various university tests.
In preparation, we would encounter problems, so post your doubts here and others will solve.
JazakAllah!

Helpful things added by different people:

What to study for A level students, added by Slash:
Click here
click here for geometry formulas by @Slash

Playlist for Physics different topics (Very good explanations!)
http://www.youtube.com/playlist?list=PLF71B362214423F9D

http://www.brightstorm.com/science (shared by XPFMember)

Helpful link shared by hassam:
http://www.youtube.com/user/ExamFearVideos

Determinants shared by @hassam

Link shared by HIMYM forever!! (Determinants)
http://tutorial.math.lamar.edu/Classes/LinAlg/DeterminantByRowReduction.aspx

Formula of some metals shared by @hassam

5 * 5 determinants method shared by @smzimran

Rotational Dynamics shared by @hassam


Quadratic equations post by @hassam

Functions, Row echelon and Angular Momentum shared by @hassam




Least count of instruments shared by @hassam

 

[smzimran]

If Z1 = 1 + i and Z2 = 2 + 3i , then |Z2 - Z1| = ?

My answer is root 5
but the book says its (root 3) i

I dont get it, probably the book is wrong here...

 

[HIMYM forever!!]

The book is definitely wrong. I mean they are asking for modulus of the difference of the two given complexes. Modulus is a distance or a magnitude. It cannot have iota (i) with it

 

[smzimran]

The book is definitely wrong. I mean they are asking for modulus of the difference of the two given complexes. Modulus is a distance or a magnitude. It cannot have iota (i) with it

Exactly, now iam beginning to realise the standard of CIE, atleast the books were never misleading!

 

[smzimran]

Another one:
The value of x and y when (x + iy)^2 = 5 + 4i

A. x = 2 , y = -1
B. x = -2 , y = 1
C. x = 2 , y = -i
D. x = 2 , y = 2

The book says the answer is A but I think none of the options are correct!

 

[HIMYM forever!!]

Lol none of the options satisfy the given equation

 

[hassam]

wonderful smzimaran@this thread/./great job......will try my best to contribute

 

[hassam]

important to know

 

[hassam]

smbody solve this
do we need to know determinnat of n by n matrix and n greater than 3.....i meean 4 by 4...and so on....as for inverses....till wat we need to know 2 by 2 and 3 by 3??

 

[HIMYM forever!!]

smbody solve this

This one's pretty simple. The answer is 0
Steps :-
1: Row3 + Row2
2: Row3 + Row1
All elements of Third row become zero so the whole determinant becomes zero

 

[hassam]

This one's pretty simple. The answer is 0
Steps :-
1: Row3 + Row2
2: Row3 + Row1
All elements of Third row become zero so the whole determinant becomes zero

i dint understand ur method.......?.....i learned the method mentioned khan acdemy videos

 

[HIMYM forever!!]

i dint understand ur method.......?.....i learned the method mentioned khan acdemy videos

You can try your method (expansion of determinant), it'll give the same answer (zero), but it'll take way more time. And in Entry tests you don't have much time to expand the determinant and then find the answer.
And Operations on Rows and columns method is easier plus it wouldn't take more than half a minute.

 

[smzimran]

You can try your method (expansion of determinant), it'll give the same answer (zero), but it'll take way more time. And in Entry tests you don't have much time to expand the determinant and then find the answer.
And Operations on Rows and columns method is easier plus it wouldn't take more than half a minute.

We are in the learning phase right now, so no shortcuts for now!

We will learn them later!

 

[HIMYM forever!!]

Equal charges are given to two spheres of different radii. What should be the potential on both?
Equal, right?

 

[smzimran]

Equal charges are given to two spheres of different radii. What should be the potential on both?
Equal, right?

No, capacitance is different!

 

[HIMYM forever!!]

No, capacitance is different!

Ah right! K then choose from the given options.
A: more on smaller sphere
B: more on larger sphere
C: equal on both
D: depends on the nature of material of sphere.
It could be both D and A :/

 

[smzimran]

Ah right! K then choose from the given options.
A: more on smaller sphere
B: more on larger sphere
C: equal on both
D: depends on the nature of material of sphere.
It could be both D and A :/

A

capacitance is inversely proportional to potential if charge is constant.

So the sphere with less capacitance (or less radius) will have more potential.

 

[HIMYM forever!!]

A

capacitance is inversely proportional to potential if charge is constant.

So the sphere with less capacitance (or less radius) will have more potential.

Yeah i get it how the answer could be A. But capaciatance also depends on medium which makes the option D correct as well. =/

 

[smzimran]

Yeah i get it how the answer could be A. But capaciatance also depends on medium which makes the option D correct as well. =/

The material used is same for both, so its constant!

 

[HIMYM forever!!]

The material used is same for both, so its constant!

Lol that is not mentioned but anyway thanks.