The Maths and Science Thread - Collection of Problems and Facts

[Bounce]

I gave it a try, I got the answer as 1/b, though I dunno if its needed in that form...

Can you please explain the method or post a snap of the solution?

 

[Varun]

Can you please explain the method or post a snap of the solution?

Yeah! For me too.

 

[P Squared]

You have to solve it using the componendo dividendo method.

 

[Kshitiz_Indian]

I can't post a snap, its horrible, I filled one page with it all.

I didn't use Componendo and Dividendo directly. I just multiplied both the numerator and denominator by the numerator, and then used the standard identities to simplify the expression. When I couldn't simplify it any more I just put the value of X. If there's a lot of trouble I can put that in writing.

 

[deathrevenge9]

TBH we solved the same question in 10th standard.The only problem is that Math isn't my subject.So I had forgotten the exact procedure.But now I have solved it too (After knowing the answer)

 

[Aussie Team]

Physics - Please solve the Question

An electromagnetic wave has an electric field strength of 145 V/m at a point P in space at time t. A parallel-plate capacitor whose plates have area 0.109 m2 has a uniform electric field between its plates with the same energy density as the answer to part a. What is the charg...

 

[Kshitiz_Indian]

I'm not really sure about this, but I think the Energy Density in a parallel plate capacitor is 1/2 x (epsylon not, don't know its character ) x E^2, where E is the Electic Field Strength. Multiply it by the volume, but then you need the distance between the plates, to get the total energy in the capacitor. Are you sure you don't have the distance between hte plates and the potential difference across the capacitor given?

 

[Harrypotter_fan]

A plane mirror is made of glass slab ( R.I.=1.5) 2.5 cm thick and silvered on back. A point object is placed 5 cm in front of the unsilvered face of the mirror. What will be the position of final image from the unsilvered face ?

Thats easy,
Assuming normal incidence, n: refractive index, t: thickness of glass, d: distance of object.

Apparent image after refraction wrt unsilvered glass,
= nd, wrt mirror = nd + t,
Image off mirror wrt itself,
= nd + t, wrt unsilvered glass = nd + 2t,
Image after refraction,
= (nd + 2t)/n.

Here wrt means with respect to.

 

[Varun]

Assuming normal incidence, n:

How do we find Normal incidence ? It hasn't been given in the question.

 

[Harrypotter_fan]

If we don't consider only near normal rays we can't take thd sin i = tan i approximation and the answer will become a function of angle of incidence and a point image will not be formed. Near normal incidence just means that the observer is directly behind the object.

 

[King Cricket]

If x + 1/x = 3

Find the value of x^5 + 1/x^5

I can't solve this one. Some help will be much appreciated.

 

[Varun]

If x + 1/x = 3

Find the value of x^5 + 1/x^5

I can't solve this one. Some help will be much appreciated.

Try multiplying (x+1/x)^3 with (x+1/x)^2. and putting appropriate values in between.

varun_rustagi added 11 Minutes and 4 Seconds later...

The answer is 123.
Shall I explain?

 

[Varun]

This thread is seeking revival..............

 

[Abhas]

Post your questions..

 

[King Cricket]

A man at a certain distance from a cliff receives the echo of a sound after x seconds. He then approaches the cliff by 'a' metre and finds the time for echo to be y seconds. Show that the velocity of sound is 2a/x-y m/s.

A little help in solving this?