Physics: Post your doubts here!

[Shimmery woods]

First P=Fv
=300kN x 40 ms-1
=1.2 x 10^7 W / 1M = 12MW

thankyou!!

 

[Metallic9896]

View attachment 62538

Nice username. Sum of vertical upwards momentum = sum of vertical downwards momentum, and sum of horizontal rightwards momentum = sum of horizontal leftwards momemtum.

Using the vertical one, total downwards momentum at end is (0.1)(8.0) = 0.8 N s

So total upwards momentum should be equal to 0.8. Both are 0.05v sin 60, so:

2 x 0.050(v) x sin 60 = 0.8
0.050 (v) = 0.8/(2 x sin 60)
v = 9.23

 

[Thelastmoment]

Nice username. Sum of vertical upwards momentum = sum of vertical downwards momentum, and sum of horizontal rightwards momentum = sum of horizontal leftwards momemtum.

Using the vertical one, total downwards momentum at end is (0.1)(8.0) = 0.8 N s

So total upwards momentum should be equal to 0.8. Both are 0.05v sin 60, so:

2 x 0.050(v) x sin 60 = 0.8
0.050 (v) = 0.8/(2 x sin 60)
v = 9.23

I just typed it in the cal till i got 800 o_o (Life hack btw when you get stuck in q's like this you gotta save time and the name, suits the moment right?)

 

[Shimmery woods]

plz tell me how to solve these type of problems e.g.

a copper wire is to be replaced by an aluminium allow wire of the same length and resistance. copper has half the resistivity of the allow. what is the ratio
diamerter of alloy wire/diameter of copper wire?
i mean every time there is a question like this i can't understand how to solve them

and like this:

fringes of separation x are observed on a screen 1.00m from a double slit that is illuminated by a yellow light of wavelength 600 nm.
at which distance from the slits would fringes of the same separation x be observed when using blue light of wavelength 400nm?

 

[Shimmery woods]

plz tell me how to solve these type of problems e.g.

a copper wire is to be replaced by an aluminium allow wire of the same length and resistance. copper has half the resistivity of the allow. what is the ratio
diamerter of alloy wire/diameter of copper wire?
i mean every time there is a question like this i can't understand how to solve them

and like this:

fringes of separation x are observed on a screen 1.00m from a double slit that is illuminated by a yellow light of wavelength 600 nm.
at which distance from the slits would fringes of the same separation x be observed when using blue light of wavelength 400nm?

 

[Holmes]

 

[Zaki ali asghar]

View attachment 62543

C?

 

[Holmes]

C?

yes
what's the reason

 

[Holmes]

Hey guys have you all gone to sleep.

 

[Shimmery woods]

Hey guys have you all gone to sleep.

we need to increase the number of nuclei present because .....a particles are deflected by large angles when they hit the nucleus of the atom ..so the only valid option is C ..by using double thickness foil number of nuclei increases nd a larger propotion of a particles are deflected

 

[Holmes]

 

[Holmes]

we need to increase the number of nuclei present because .....a particles are deflected by large angles when they hit the nucleus of the atom ..so the only valid option is C ..by using double thickness foil number of nuclei increases nd a larger propotion of a particles are deflected

thanks

 

[Holmes]

 

[Shimmery woods]

View attachment 62545

wind resistance increases with speed ---also they said that wheel friction is constant..at speed 0 ..wind friction will also be 0..so 8 kN is the value of wheel friction...at 200 speed 40-8 = 32 KN is wind resistance so ratio would be 32/8 = 4

 

[shahzaib ihsan]

guys look at question 11 on this paper:
http://www.teachifyme.com/wp-content/uploads/2016/08/9702_s16_qp_11.pdf

how is the 2nd column correct? (mv sin30=MV sin40)

 

[Holmes]

View attachment 62544

 

[Holmes]

 

[shahzaib ihsan]

View attachment 62546

View attachment 62547

the answer is c?

 

[Holmes]

the answer is c?

yes

 

[MarcosT200]

we first need to find the voltage in the external resistance. so using v=ir
hence v=5.5v. since the all of the components are parallel to each other they all have an terminal potential difference of 5.5v
current going into the junction= output of junction.
so the current going into the internal resistance is 0.25A. 0.5/2 as both components have the same p.d and internal resistance they both have the same current
simply then use the formual
terminal p.d=Emf-Ir
5.5=6-0.25r
hence r is 2 ohms

I have a question:

Since the terminal pd's of the battery's in parallel are equal, isn't there supposed to be NO current flowing through the batteries? And therefore the 0.5 A only come from one of the batteries?

Thank you,