IIT JEE , AIEEE Forum - Physics , Mechanics

abhijeet_0201

statement1:two simple harmonic motion are given by

y1=10cos(wt+/6) and y2=10(coswt +

3 sinwt) the ratio of respective amplitudes is 1:2

satement 2:the simple harmonic motion y2 is the sum of two simple harmonic motions

i m confused i think the ans shud be (A) but ans given is (B)

what do u think??????

karthik2007

What are the options? What do u mean by A?

abhijeet_0201

i m sorry i thought ppl wud be familiar with assertion reason ques

A-both are right,2 explains 1
B-both are right , 2 is not the reason for 1
C-1 is right,2 is wrong
D-1 is wrong ,2is right

karthik2007

Both the statements can be proved easily.

The second expression is simply 20(coswt-pi/6)

And the second one is a sum of 2 shm's, again clear.

But both the statements are totally irrelevant wrt each other.

abhijeet_0201

i accept ur ans bbut i am always confused b/w (A) and (B)

karthik2007

What is there to get confused buddy? It is clear that the second shm is a sum of two shms, But how does it explain that the amplitude is 20? YOU SIMPLY CANNOT ADD THE AMPLITUDES OF TWO SHMS! You have got to combine them into a single term using trigonometrical shortcuts. Here by sheer luck, we get the sum of the two amplitudes as 20, but it is totally wrong. Keep that in mind.

abhijeet_0201

okay for now im satisfied ...thanks...but ill post some more assertion reason
which tend to confuse me

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