AS Physics P1 MCQs Preparation Thread.

ashoo123

ashoo123

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snowbrood said:
http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s12_qp_13.pdf Q13 need ur help guys
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q13
okk...I'm not great at explaining but here goes....

Wx=Ly where Ly increases, so the RHS must be decreased. Now, the horizontal force would have no affect on it, as the previously mentioned forces are downwards (think of it as when u resolve forces in mechanics, if u take maths)
So A and B dont count.
The reaction force acts upwards, hence opposite to W and L, therefore if R were to shift to the right, the total of the RHS will lower
Wx=Ly-Rd , not sure if this equation is right, but the basics is that R would cancel out part of the force applied by L
Therefore the ans is D

Hope that helped! ;)
 
ashoo123

ashoo123

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Santiago Carthorla said:
Can anyone explain to me Q15,17,18,23,29 and 37! Will be much grateful and thank you in advance! http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s12_qp_12.pdf
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q15)
After the position of the spindle has been changed it will topple in the anti-clockwise direction, so to keep it in equilibrium the torque must act in clockwise direction....Since the force would be acting from the centre, the distance is L/4
Hence..ans will be D

q17)
Add work done of each block separately

Block 1: not moved..no WD
Block 2: mgh
Block 3: mg2h
Block 4: mg3h

Therefore total WD= mgh+2mgh+3mgh = 6mgh ----> ans B

q23)
The answer cannot be A and B as the gas pressure must be higher than atm pressure
At any point on the same level pressure is the same...hence at the point indicated
gas presure = atm. pressure + liquid pressure
= 100,000 + 1000*9.81*5 =1.5x10^5 Pa
ans ---> C

q29)
v=fλ
v=f/t
So t=λ/v (in this case v=c)
Since distance from XY to any point on the wavefront marked P is 3λ
t=3λ/c
answer ---> C

q37)
As inferred from the circuit diagram, both lamps will light up
But since the connection is in series and only one of them is supposed to light up in normal conditions, the voltage will be split and both lamps will light up dimly...hence D
 
princessnoor

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Thought blocker

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8)
you know that gradient of the displacement-time graph is velocity. In this situation, initially, velocity will increase as air resistance acting on it is lesser than acceleration due to gravity and after a while, velocity becomes constant (air resistance=acceleration due to gravity). Bearing this in mind, as initially velocity increases, gradient MUST increase and then when velocity gets constant, gradient becomes constant by implied by the straight line.

10)
F is always in the same direction with a because F is the product of a and a scalar m. Note that v is not always in the same direction with F or a.
you'll think how is that possible? if F and a are in the same direction, shouldn't v be in that direction too?
answer is Let's say we have an object moving to the right, i.e. the vector v is pointing to the right. Then, we pull the object to the left, i,e. F is pointing to the left. This causes the object to have an acceleration in the opposite direction of the initial velocity.
 
Haya Ahmed

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Thought blocker said:
8)
you know that gradient of the displacement-time graph is velocity. In this situation, initially, velocity will increase as air resistance acting on it is lesser than acceleration due to gravity and after a while, velocity becomes constant (air resistance=acceleration due to gravity). Bearing this in mind, as initially velocity increases, gradient MUST increase and then when velocity gets constant, gradient becomes constant by implied by the straight line.

10)
F is always in the same direction with a because F is the product of a and a scalar m. Note that v is not always in the same direction with F or a.
you'll think how is that possible? if F and a are in the same direction, shouldn't v be in that direction too?
answer is Let's say we have an object moving to the right, i.e. the vector v is pointing to the right. Then, we pull the object to the left, i,e. F is pointing to the left. This causes the object to have an acceleration in the opposite direction of the initial velocity.
Click to expand...
for Q8 why not D ... and Isn't the speed should decrease because as air resistance increase the speed decrease ?
 
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