Physics: Post your doubts here!

[dwightedknight]

38th question, I'm slightly confused. Can someone help?

p.d. across P = p.d. across R

So P/Q = R/S

 

[Mush999]

p.d. across P = p.d. across R

So P/Q = R/S

thank you!

 

[A*****]

Help plz

 

[Kanekii]

View attachment 64098

Help plz

is it B?

 

[A*****]

is it B?

A

 

[Kanekii]

A

huh im confused too now..

 

[dwightedknight]

View attachment 64098

Help plz

Length of 1 turn is pi*D. Length of n turns is pi*D*N. Cross section area = pi*d^2/4.

 

[A*****]

Length of 1 turn is pi*D. Length of n turns is pi*D*N. Cross section area = pi*d^2/4.

Shouldn't the 2 resistances be added?

 

[Kanekii]

Shouldn't the 2 resistances be added?

no as the resistance is only from copper wire due to its length and area

 

[Kanekii]

help

 

[dwightedknight]

View attachment 64099 help

a = -F/m. s = 100. v = 0.
v^2 = u^2 + 2as
u = sqrt(v^2 - 2as) = sqrt(200F/m)

When u = sqrt(200F/m), a = -0.8F/m and v = 0,
v^2 = u^2 + 2as, s = (v^2 - u^2)/2a
s = - sqrt(200F/m)^2/(-0.8*2F/m) = (200F/m)/(1.6F/m) = 125.

 

[A*****]

Why is it not A?

 

[dwightedknight]

View attachment 64100


Why is it not A?

Waves are in phase. Which means that their path difference is 0. Which means that their displacement is same. So the answer is C.

When the ratio is -1, their displacements are in opposite direction. This means that when the meet at a point, their resultant displacement is 0. This means that it will be a node.

 

[Ebrahim12]

View attachment 64100


Why is it not A?

This diagram shows how the superposition of an incident and reflected wave results in a stationary wave.

The waves never have opposite displacements at the antinodes, so it can't be A.

 

[dwightedknight]

2(x+5) + 1 = 7 + 2x. Please help.

 

[A*****]

Why can't it be B or C?

 

[A*****]

2(x+5) + 1 = 7 + 2x. Please help.

What is this??

 

[Mush999]

2(x+5) + 1 = 7 + 2x. Please help.

This equation is not correct I guess, there's no solution. Is there a question about it?

 

[Mush999]

View attachment 64101

Why can't it be B or C?

Because area under Force extension graph is always the work done in stretch the wire, given no plastic deformation has occurred. If plastic deformation occurs then the area under the graph beyond yield point, is the energy used to permanently deform the wire
t
Not B because the wire is extended plastically and it will not go back to it's original lenght, so the energy is use up in misplacing the atoms in the structure of the wire

Not C because the first part of the graph where the wire extends elastically, the energy is used strechs the wire not deform it permanently thus no heat.

D is the right option

 

[A*****]

Why can't it be C??