Physics: Post your doubts here!

[nehaoscar]

Why C?
The current flows from left to right so to increase the current accross the sliding contact, shouldn't it be D??

 

[princess Anu]

ans is A :/

 

[DaniyalK]

ans is A :/View attachment 54892

Resistance = resistivity * (length/x-sectional area)
length is halved and area is doubled so resistance is 1/4th of the original.

 

[princess Anu]

Resistance = resistivity * (length/x-sectional area)
length is halved and area is doubled so resistance is 1/4th of the original.

but then why isn't this concept applicable here? here the ans is C, why ? :S how is it different?

 

[princess Anu]

HELP

Ans is C

 

[DaniyalK]

View attachment 54893

but then why isn't this concept applicable here? here the ans is C, why ? :S how is it different?

It's not the same. In the previous question, volume was same but length and area were different.
In this one, volume and length are both same.

 

[Studydayandnight]

HELPPP

Correct answer is C.

 

[princess Anu]

It's not the same. In the previous question, volume was same but length and area were different.
In this one, volume and length are both same.

Oh, I get it.. Thanks A lot
Can you try the others too please

 

[DaniyalK]

HELP

Ans is C

Driving force = ma = 1800 * 2 = 3600N
Tension in first cable from left = T0
Motion of powered vehicle:
3600 - T0 = 200(2)
T0 = 3200
Motion of cart 1:
T0 - T = 400(2)
T = 2400N

HELPPP

Correct answer is C.

Moment due to weight = 0.1 * 10 * 9.81 = 9.81 clockwise
Moment due to pulley = 0.02*9.81*60 = 11.77 anti cw
difference is 1.962 anti cw, so we need 1.962 in cw direction, which we get by placing 50g on the 44cm mark.

 

[princess Anu]

It's not the same. In the previous question, volume was same but length and area were different.
In this one, volume and length are both same.

help me with this pleaseee. Ans is A

 

[DaniyalK]

help me with this pleaseee. Ans is A View attachment 54896

KE = 0.5 * 50 * 3 * 3 = 225
mgh = 225
h = 0.46m
cos(theta) = 3.54/4

 

[nehaoscar]

How B??
Y = FL/AX
L halves and A is reduced by 1/4th so shouldn't it be C??

 

[nehaoscar]

How B??
strain is deltaL/L so it it that delta l is proportional to L?

 

[nehaoscar]

Why is resultant force zero?

 

[Xtreamer]

Anyone Got some time management tips PLEASE SHARE!

 

[Xtreamer]

View attachment 54900
Why is resultant force zero?

Cuz Electric Field exerts a constant force so +Q and -Q 's have equal forces

 

[Ahmed Aqdam]

View attachment 54898
How B??
Y = FL/AX
L halves and A is reduced by 1/4th so shouldn't it be C??

Wire is of same steel so same Young Modulus. The difference will be in extension.

View attachment 54899
How B??
strain is deltaL/L so it it that delta l is proportional to L?

Compression is proportional to length but also inversely proportional to area of cube.

 

[princess Anu]

help me with this pleaseee. Ans is A View attachment 54896

Thanks a TON!
This is the last one, please
Ans is C

 

[Ahmed Aqdam]

Thanks a TON!
This is the last one, please View attachment 54901
Ans is C

All linear dimensions are one tenth so volume will be 1/1000. Same material is used so density is same and mass should also be 1/1000 to maintain same density. Weight depends on mass so it will also be 1/1000.
Area is 1/100 as 1/10 is squared.
Hence stress is (1/1000)/(1/100)=0.1

 

[Studydayandnight]

HELPPP!!!!!!!!

What's the answer?!