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AS Physics P1 MCQs Preparation Thread.

h4rriet

h4rriet

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HongYue said:
Question 12, 14, 26, 28, http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w09_qp_11.pdf
Thanks !!
Click to expand...

12. You have to consider the angles between T1 and R1 and T2 and R2. T1 cos(angle) gives you R1. What happens to cos(angle) if the angle decreases?
14. At the highest point of a parabolic trajectory, the vertical component of the velocity = o. So the K.E. can come only from the horizontal component, which is constant throughout.
26. Use sin90=nxlambda, then multiply by 2 (because you're taking the maxima on both sides of the middle maximum) and add 1 (the middle maximum).
28. Weight acts downwards so since it's in equilibrium the electric force has to act upwards. Since the plate up is positive and attracting the drop, that drop has to have a negative charge.
 
HongYue

HongYue

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h4rriet said:
12. You have to consider the angles between T1 and R1 and T2 and R2. T1 cos(angle) gives you R1. What happens to cos(angle) if the angle decreases?
14. At the highest point of a parabolic trajectory, the vertical component of the velocity = o. So the K.E. can come only from the horizontal component, which is constant throughout.
26. Use sin90=nxlambda, then multiply by 2 (because you're taking the maxima on both sides of the middle maximum) and add 1 (the middle maximum).
28. Weight acts downwards so since it's in equilibrium the electric force has to act upwards. Since the plate up is positive and attracting the drop, that drop has to have a negative charge.
Click to expand...

14. So why is the answer 0.5E instead of E
28. Why g/E instead of E/g
 
ShaanSiddiq090909

ShaanSiddiq090909

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ahmed abdulla said:
use total momentum before collision=total momentum after collision
therefore, 2*2=1*v
therefore speed of 1 kg trolley is 4..
now u have mass and velocity of both trolleys , right ?
find kinetic energy of both ... and simply add them !
hope that helps ! ;)
Click to expand...

BTW bro thankss alott.. this was really very helpful! :)
 
ZainH

ZainH

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h4rriet said:
13. All you gotta do is choose a pivot and work out the moments on either side of it...
14. mgh=1/2m(v^2). mgh/2 = 1/2m(x^2). Eliminate m, g, and 1/2. Cross multiply.
15. Find the angle to the horizontal of the slope. Then find the component of the weight parallel to the slope. Then use F=ma to find the acceleration. Then use a suvat. You can also do it using 1/2m(v^2)=mgh.
34. Resistance = ql/A. A=lxl, so Resistance=ql/lxl. l and l cancel out; R=q/l. l^3=V, so l = cube root of V = V^(1/3), so R=q/V^(1/3).
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For Q13. there is already a pivot, so why would we choose one? It doesn't work with the given one.
For Q.14 I have no idea what you did..
I understood Q15. thank you.
And also I do not know what you did in Q34.

Can you explain more please?
 
h4rriet

h4rriet

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ZainH said:
For Q13. there is already a pivot, so why would we choose one? It doesn't work with the given one.
For Q.14 I have no idea what you did..
I understood Q15. thank you.
And also I do not know what you did in Q34.

Can you explain more please?
Click to expand...

Well, you do use the pivot they've given. (20x60)+(100x10)=50x.
14. The steel sphere is dropped from a height of h. It has g.p.e.=mgh. When it reaches the ground, all its g.p.e. turns into k.e. So mgh=1/2m(v^2). Now it's held at h/2 metres above the ground. So the g.p.e. it has is mgh/2. This too will turn into k.e.
34. I just used the formula for Resistance, Resistivity, Area and Length. R=ρl/A. Now we know that A = l x l. So we can replace A in the equation with l x l. That'll make it R=ρl/l x l. l and l cancels out (from the numerator and denominator) leaving R=ρ/l. Now we know that Volume = l x l x l, so Volume = cube root of l, which is also written as V^(1/3). So we can replace l with V^(1/3). R=ρ/V^(1/3).
 
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