Physics: Post your doubts here!

[Wkhan860]

View attachment 55121 I need the working and explaination for these two questions.plz help me

Qtn no 22 is A i reckon
To find efficiency use Energy output/Energy Input
Energy output is (P*t)
Energy input is (energy frm all coal)*number of trains
Thus PS/NMJ
In bith qtns use the efficiency formula

 

[raining]

how to solve (i) ?

 

[raining]

how to solve (I) ??

 

[shinnyyy]

Qtn no 22 is A i reckon
To find efficiency use Energy output/Energy Input
Energy output is (P*t)
Energy input is (energy frm all coal)*number of trains
Thus PS/NMJ
In bith qtns use the efficiency formula[/QUOTE

Energy input is (energy frm all coal)*number of trains??? HOW ? Shouldn't it be just the energy from all coal?

 

[shinnyyy]

There's another question from forces unit :
If a car is moving in a horizontal direction then in which direction the net force will act on the car.secondly how we'll draw the vector diagram for this question.

 

[shinnyyy]

Can anyone explain me how to solve Q8?

 

[shinnyyy]

q21?

 

[shinnyyy]

How we have to solve this question and what's the logic behind the ans.

 

[shinnyyy]

Bilal Khan before leaving plz help me with the questions(doubts) which I have posted above

 

[Wkhan860]

View attachment 55139
Can anyone explain me how to solve Q8?

For the goods train apply the formula ((u+v)/2)*t
N for express train use s=ut+0.5at^2
Solve them simultaneously or substitute the values
U will get 40sec as ans (D)

 

[shinnyyy]

For the goods train apply the formula ((u+v)/2)*t
N for express train use s=ut+0.5at^2
Solve them simultaneously or substitute the values
U will get 40sec as ans (D)

I have tried to solve the question but I'm stuck in the mid, now idk how to solve it further
As you have told to use that use but in the question V is not given so how how I'll know if u=10 or if v= 10
And one thing more, why we'll solve that simultaneously? ?
N can u plz solve the other two questions as well ..please

 

[Wkhan860]

View attachment 55158 I have tried to solve the question but I'm stuck in the mid, now idk how to solve it further
As you have told to use that use but in the question V is not given so how how I'll know if u=10 or if v= 10
And one thing more, why we'll solve that simultaneously? ?
N can u plz solve the other two questions as well ..please

Thy hav said constant speed....whch means thn speed will remain same...so v nd u will both be 10
Theres no need to solve simulataneously if u dnt want to.
'S' will be same so ((10+10/2))*t=(0*t+0.5*0.5*t^20

 

[shinnyyy]

Thy hav said constant speed....whch means thn speed will remain same...so v nd u will both be 10
Theres no need to solve simulataneously if u dnt want to.
'S' will be same so ((10+10/2))*t=(0*t+0.5*0.5*t^20

I got it ^_^
Thanks
Please explain me the remaining questions too .

 

[Wkhan860]

I got it ^_^
Thanks
Please explain me the remaining questions too .

Uhm..wait lemme try
I couldnt do the density qtn ill try the other 1

 

[shinnyyy]

Uhm..wait lemme try
I couldnt do the density qtn ill try the other 1

I have tried to solve that density one but idk what I'm doing in that question, can u plz check one that too cz it's repeated thrice in p.p

 

[Wkhan860]

I have tried to solve that density one but idk what I'm doing in that question, can u plz check one that too cz it's repeated thrice in p.p

I have tried it 3 times nd got it wrong every time

 

[shinnyyy]

I have tried it 3 times nd got it wrong every time

Haha then hi5
even my sir couldn't solve that tch tch
But what about the other one ?? Idk why they have shown a force coming out of the pivot, I don't think so if I have studied any such thing from the coursebook.

 

[Wkhan860]

Haha then hi5
even my sir couldn't solve that tch tch
But what about the other one ?? Idk why they have shown a force coming out of the pivot, I don't think so if I have studied any such thing from the coursebook.

Actually my sir did solve tht qtn but i forgot the method
Its 'C' I thnk....its a fluke tbh...T will be greatest as u need force greater than doors 'W' to move it..no idea abt 'H'
Or use the triangle of force method

 

[Liv2Stdy]

View attachment 55140 q21?

The pressure at the bottom is given. This is the sum of the pressures at the bottom of the layer of oil and at the bottom of the layer of water. So all you need to do is add these two pressures. If you dont get it, I'll be happy to explain it further. Answer is D.

 

[shinnyyy]

The pressure at the bottom is given. This is the sum of the pressures at the bottom of the layer of oil and at the bottom of the layer of water. So all you need to do is add these two pressures. If you dont get it, I'll be happy to explain it further. Answer is D.

View attachment 55170

Oh I got it ..tysm
And can you plz explain me the other question aswell?