Physics MCQs thread.

[yubakkk]

http://www.xtremepapers.me/CIE/International%20A%20And%20AS%20Level/9702%20-%20Physics/9702_w09_qp_11.pdf
Please explain Question 26.

Total maxima = 2 x highest maxima + 1

highest maxima = line spacing/wavelength

line spacing = 1/(300 x 10^-3)

highest maxima = (1/300x10^-3) /( 450 x 10^-9)

= 7.4 x 10^6

2(7.4 x 10^6) + 1 = 14.8 x 10^7

= 15 when you round it off

So answer is D

 

[examfearz]

Anyone?? How is the answer D?...i cant understand

 

[examfearz]

I know this has been askd before but can anyone tell me the reasoning behind this...I know the k.e is not conserved but how can we tell exactly what the chng in momentum will be?

 

[yubakkk]

change in momentum is mv-mu
so lets take initial direction as positive
-2mv-2mv=-4mv
so change is 4mv

 

[examfearz]

Yeah I thought the same thing but the Answer is C!! :%)

 

[sniper7137]

It cant be A or B 'cos those changes won't give a speed which indicates a rebound. It can't be D cos a 4mv change means an elastic collision in which the relative speed of approach is the same as the relative speed of rebound. The question says its an inelastic collision meaning some of the momentum is transferred to the wall.

This only leaves option C as it indicates a rebound speed which is less than the approach speed. Hope this helps.

 

[sniper7137]

@Yubakk. You don't round it off. You round it 'down' to the previous integer. This is a rule when calculating the number of orders. Always remember it.

 

[Mueez]

http://www.xtremepapers.me/CIE/Internat ... _qp_11.pdf
Q.16 nd Q.22 plzz

 

[RafaySid]

I know this has been askd before but can anyone tell me the reasoning behind this...I know the k.e is not conserved but how can we tell exactly what the chng in momentum will be?

The answer is C guys. Look, the initial momentum is 2mv. Since it's in an INELASTIC collision and it's said that it'll rebound, meaning it will lose it's speed. So as mass is constant, only C is the option where the rebound speed is less than the initial (2v>v). So m[2v-(-v)] = 3mv.

 

[RafaySid]

Anyone?? How is the answer D?...i cant understand

As this is a simple addition/subtraction one, add the two uncertainties = 0.03. The absolute answer is 0.44. Now calculate the %, 0.03/0.44 x 100 = 6.818 ~ 7.

 

[Hateexams93]

I know this has been askd before but can anyone tell me the reasoning behind this...I know the k.e is not conserved but how can we tell exactly what the chng in momentum will be?

The answer is C guys. Look, the initial momentum is 2mv. Since it's in an INELASTIC collision and it's said that it'll rebound, meaning it will lose it's speed. So as mass is constant, only C is the option where the rebound speed is less than the initial (2v>v). So m[2v-(-v)] = 3mv.

u said mass is constant which is 2m , so why did u write m at the end ?

 

[rabib2013]

can anyone explain this to me?

 

[RafaySid]

I know this has been askd before but can anyone tell me the reasoning behind this...I know the k.e is not conserved but how can we tell exactly what the chng in momentum will be?

The answer is C guys. Look, the initial momentum is 2mv. Since it's in an INELASTIC collision and it's said that it'll rebound, meaning it will lose it's speed. So as mass is constant, only C is the option where the rebound speed is less than the initial (2v>v). So m[2v-(-v)] = 3mv.

u said mass is constant which is 2m , so why did u write m at the end ?

Mass is a constant 'm'. Speed changes from 2v to v.

 

[RafaySid]

can anyone explain this to me?

It's quite obvious that electrons are in total random motion everywhere even when electricity is not being passed. When a current is passed they move in an order, so A is the answer.

 

[DeathDealer]

Hey.......cn any1 explain dm plzzzzzz itx june 06

http://www.xtremepapers.me/CIE/Internat ... 6_qp_1.pdf

Ques 9 & 33

 

[Xthegreat]

Hey.......cn any1 explain dm plzzzzzz itx june 06

http://www.xtremepapers.me/CIE/Internat ... 6_qp_1.pdf

Ques 9 & 33

Q9. the y-axis is velocity
at A. the mass is moving up and reaches its max height at B.
then at C. the mass moves down and reaches it's max velocity
to be at the lowest position, the mass have to stop moving meaning when it loses all its energy, it stops making D the answer.

 

[Zizu1992]

Which statement about Newton’s laws of motion is correct?
A The first law follows from the second law.
B The third law follows from the second law.
C Conservation of energy is a consequence of the third law.
D Conservation of linear momentum is a consequence of the first law.

Please explain why the answer is A?

 

[diwash]

Can anyone help me with Qno 8 of Oct/nov 10 paper 12?
http://www.xtremepapers.me/CIE/International A And AS Level/9702 - Physics/9702_w10_qp_12.pdf

 

[Saturation]

Which statement about Newton’s laws of motion is correct?
A The first law follows from the second law.
B The third law follows from the second law.
C Conservation of energy is a consequence of the third law.
D Conservation of linear momentum is a consequence of the first law.

Please explain why the answer is A?

The first law follows from the second law:
the 2nd law states F=ma , so if F=0 , a=0
the 1st law states that if no resultant forces act on a body it will continue in it's original state of motion or rest , which means there will be no change in velocity , hence a = 0 , which follows from the 2nd law!

and the other "statement" which is correct is:

The conservation of linear momentum is a consequence of the 3rd law .

 

[DeathDealer]

Ques 21........y v add both pressure ov liquid n oil ?
Explain plzzzzzz

http://www.xtremepapers.me/CIE/Internat ... 6_qp_1.pdf