• We need your support!

    We are currently struggling to cover the operational costs of Xtremepapers, as a result we might have to shut this website down. Please donate if we have helped you and help make a difference in other students' lives!
    Click here to Donate Now (View Announcement)

Physics MCQs thread.

Messages
426
Reaction score
4
Points
0
arlery said:
Why is the answer A?
Apparently, the thicker spring has higher k, and the thinner spring has lower k. the spring with the lower k can be affected ( extended ) by small amount of force such as wind which gives an error in determining the mass. in that case, it should be kept in a rigid box to insulate it from any other external forces ( wind ). whereas in the thicker spring, the external forces are negligible because it needs much more force to be extended ( since it has a high k value). So A is the answer.
 
Messages
63
Reaction score
1
Points
16
can anyone please explain me the relationship between upthrust, weight and air resistance of a falling body in a fluid pls i just dont seem to understand it.... please someone explain it in details...
 
Messages
426
Reaction score
4
Points
0
Arshiful said:
can anyone please explain me the relationship between upthrust, weight and air resistance of a falling body in a fluid pls i just seem to understand it.... please someone explain it in details...

weight is the gravitational force acting on a body, it is a vector quantity which acts in the downward direction ALWAYS. it has a formula which is
weight = mass x gravity ( g = 9.81 ).

upthrust: is the upward force exerted on an object due to the pressure difference of the upper and lower surface of that object ( as they have different pressures due to different levels ) as it falls in the air or in a fluid ( higher in the fluids than in the air ). it acts upwards ALWAYS.

air resistance is the resistive force acting in the opposite direction of a falling/moving object, it increases as the velocity of the object increases. if air resistance is equal to the weight or acceleration, then the object will move/fall with steady speed.
 
Messages
426
Reaction score
4
Points
0
aamir12345 said:
@hassam plz tell me the answers of above questions and plz explain that grating question
he has already mentioned the answers, check the previous posts
 
Messages
220
Reaction score
0
Points
26
xHazeMx said:
arlery said:
Why is the answer A?
Apparently, the thicker spring has higher k, and the thinner spring has lower k. the spring with the lower k can be affected ( extended ) by small amount of force such as wind which gives an error in determining the mass. in that case, it should be kept in a rigid box to insulate it from any other external forces ( wind ). whereas in the thicker spring, the external forces are negligible because it needs much more force to be extended ( since it has a high k value). So A is the answer.

Ok, my reason is completely different! The one with the lower constant is kept in the box,cause : Picture this, as you add small amounts of weight, the spring with the lower k will stretch, instead of the higher k. So as we keep adding small masses, which keep increasing in weight, the spring with the lower K keeps stretching, until a point where it comes in contact with the box, preventing it from stretching further. So when larger masses ( the masses which are added after the spring with the lower K has fully stretched) are added, the spring with the HIGHER k , will start to stretch, which will result in lower sensitivity for the "large" masses.
The opposite would have happened with arrangement C, where the spring with the lower K will keep on stretching and eventually break!

Hope you got it! :friends:
 
Messages
1,800
Reaction score
1,800
Points
173
Since path difference for destructive interference is
= S2P -S1P
=(2n-1)lamda/2

S2P = (I1 + 12) & S1P = (I2 + I4)

we replace n with m and we get (I1 + 12) - (I2 + I4) = (2m+1)lamda/2

Hope you get it. :)
 
Messages
138
Reaction score
13
Points
28
a b c are not correct because they do not give the path difference.. E is for constructive interference.. so its D!
 
Messages
1,800
Reaction score
1,800
Points
173
How can I solve this one?
 

Attachments

  • untitled.PNG
    untitled.PNG
    52.5 KB · Views: 77
Top