Physics: Post your doubts here!

[KurayamiKimmi]

Hi everybody can anyone please solve this question on simple harmonic motion?
A metal bob of 0,25 kg is suspended from a string of length 0.40 m .It is pulled up in such a way that is centre of mass is rises by 20cm above its mean position.
Find the maximum tension in the string .
Thank you for any help

 

[InnocentAngel]

LOL ti cool
But it was a nice paper(apart from some silly mistakes)

Yeah some silly mistakes too im not gettng full marks for sure

 

[AhShun]

Yeah some silly mistakes too im not gettng full marks for sure

wow... u were expecting full marks. u must be very good
keep cool and relax a little, u should be working fine cuz it's not already over yet

 

[emkay]

has anyone done m/j 2012 p33? and can someone can get me the ms of p1, oct/nov 2002?

 

[tawab]

plz provde the answers of the compiled p1 questions

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[Silent Hunter]

http://www.xtremepapers.com/papers/...and AS Level/Physics (9702)/9702_s04_qp_1.pdf


Questions : 16,25,33

 

[MysteRyGiRl]

http://www.xtremepapers.com/papers/...and AS Level/Physics (9702)/9702_s06_qp_4.pdf
need help wd Q6 a)c)
Q 7 c)
Q 8
can any1 plz explain??

 

[hussamh10]

plz can anyone help me with practicle in question no 2 when it asks about that compare the relationship or what is the relation ship where we have to fin the values of K and how you determined the sig figure how do you do that????

 

[emkay]

plz can anyone help me with practicle in question no 2 when it asks about that compare the relationship or what is the relation ship where we have to fin the values of K and how you determined the sig figure how do you do that????

once you've calculated the two different values of k, find their percentage and if the result is greater than 80% say it is valid or your calculations support the suggested relationship. i.e k1=25 and k2=56 use, 25/56*100 which gives 45%. that means the calculations does not support the result (as 45% is less than 80%)

 

[KurayamiKimmi]

can someone solve this question please :/

A metal bob of 0,25 kg is suspended from a string of length 0.40 m .It is pulled up in such a way that is centre of mass is rises by 20cm above its mean position.
Find the maximum tension in the string .

 

[Meo]

http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s04_qp_1.pdf


Questions : 16,25,33

I'm not good at explaining things but I'll try my best.

for 16.
A. The kinetic energy of the ball is greatest at the greatest height attained.
This is not true because, at the greatest height, the velocity is 0 therefore the kinetic energy is 0.

B. By principle of conservation of energy, the total energy of the ball is constant throughout the motion.
I think this is correct, because there is no energy loss throughout this motion. (i.e. no work against air resistance.)

C. By principle of conservation of momentum, the momentum of the ball is constant throughout the motion.
Wrong, because momentum is the product of mass and velocity, and you should know that throughout the motion, the velocity is not constant. There is acceleration. (9.81/-9.81 depending from where you at it)

D. The potential energy of the ball increases uniformly with time during the ascent.
The keyword to this option is 'uniformly'. It's true the fact that as you move upwards, the gravitational potential energy increases. BUT it will increase uniformly if and only if it moves upwards with uniform velocity. But again, you have acceleration.

So the answer is B.

I'm not quite sure about 25, sorry, but for 33, the answer is C because the fall in voltage is due to the existing PD across the internal resistance and to calculate for this PD (fall in voltage).
V=IR
you will need the current and the resistance.

 

[Silent Hunter]

I'm not good at explaining things but I'll try my best.

for 16.
A. The kinetic energy of the ball is greatest at the greatest height attained.
This is not true because, at the greatest height, the velocity is 0 therefore the kinetic energy is 0.

B. By principle of conservation of energy, the total energy of the ball is constant throughout the motion.
I think this is correct, because there is no energy loss throughout this motion. (i.e. no work against air resistance.)

C. By principle of conservation of momentum, the momentum of the ball is constant throughout the motion.
Wrong, because momentum is the product of mass and velocity, and you should know that throughout the motion, the velocity is not constant. There is acceleration. (9.81/-9.81 depending from where you at it)

D. The potential energy of the ball increases uniformly with time during the ascent.
The keyword to this option is 'uniformly'. It's true the fact that as you move upwards, the gravitational potential energy increases. BUT it will increase uniformly if and only if it moves upwards with uniform velocity. But again, you have acceleration.

So the answer is B.

I'm not quite sure about 25, sorry, but for 33, the answer is C because the fall in voltage is due to the existing PD across the internal resistance and to calculate for this PD (fall in voltage).
V=IR
you will need the current and the resistance.

i appreciate your answer

thank you

 

[MysteRyGiRl]

isnt any1 giving A2??????????????????????????????? where r da A2 ppl ?

 

[hussamh10]

once you've calculated the two different values of k, find their percentage and if the result is greater than 80% say it is valid or your calculations support the suggested relationship. i.e k1=25 and k2=56 use, 25/56*100 which gives 45%. that means the calculations does not support the result (as 45% is less than 80%)

Wanted to ask another thing that if in Q2 for example it asks to time when ball travels from Mark A to Mark B in a bottle full of water when we time it we must take two readings then what will be the absolute error we should take to calculate % error.

 

[emkay]

wait. o.1 it is, as the least count in the stopwatch is 0.1.

 

[panda222]

has anyone done m/j 2012 p33? and can someone can get me the ms of p1, oct/nov 2002?

Google free exam papers. They have those earlier years as well.

 

[DumbIdiot]

what does this mean - "testing against a criterion specified by the candidate"
it is in most of the practical papers where we need to say whether the suggested relationship is right

 

[raamish]

Physics A2 radioactivity question:
No= 1* 10^15
decay constant= 0.02 s-1
t= 20 s

N=No e (-d.c* t)
how do we use the ex in calculator in this question? ty

 

[123dawg]

isnt any1 giving A2??????????????????????????????? where r da A2 ppl ?

i am an A2 andi am hiding under a rock cuzz i dont want to face the paper

 

[raamish]

lol ;D