physics mcqs help required URGENTLY!

[aisha231]

Kindly help me with a few questions of physics mcqs.

m/j08 q24
m/j09 q11, q15, q16

 

[Zenzenzen]

Kindly help me with a few questions of physics mcqs.

m/j08 q24
m/j09 q11, q15, q16

M/J08 Q24:
This is a trick question. The question says "another wire of the same steel." If you read the definition of the young modulus, it is defined as having the same value if its the same material. That is why the answer is C. The young modulus doesn't change if you do not change the material.

M/J09 Q11:
S and Q are obviously equal.
For P and R you have to remember gravity is also acting on the sphere. So the total downward force is P + W. In the diagram, the only upward force is R. So if P + W = R, then R > P. So therefore the answer is A.


M/J09 Q15:
If you open the tap, half of the water will go to the other container.
Mass and height will be halved.
PE = mgh
Change in PE = (m/2) x (h/2) x g
Change in PE = (mgh/4)
Therefore answer is B.

M/J09 Q16:
You could just use simple elimination for this question.
Choices A and D are incorrect because liquids do more than just vibrate.
B is incorrect because the molecules of a solid do not move (even slowly), they only vibrate.
Therefore the only correct choice left is C.

Hope this helped ^_^

 

[aisha231]

Thanku!
that really helped.
Though i typed in the wrong question number :S
it wasnt 16, it was 18.
God!
Im sooo disoriented! :S

Anyway, thanku soo much!

 

[Rockstar3143]

even question 18 is not much difficult.
If the height on the RHS is increased by h, it means that the liquid level on the LHS is also decreased by h. Thus the total pressure = increase in pressure at RHS+ increase in pressure at LHS
=ρgh+ρgh
=2ρgh.

hope that u understood.