IGCSE PHYSICS DOUBTS HERE !!!!

[~ Miss Relina ~]

What are you talking about ?

The mark scheme says :

EDIT : Look carefully at the graph. It becomes PERFECTLY horizontal at exactly 4.2s.

oh yes sorry but do u understand why the first correct answer was 1.6-1.8 s

[~ Miss Relina ~]

help plz

[........]

Distance = area under graph

Area=1/2(10+9) * 0.6  (area of trapezium)

5.7 m

[~ Miss Relina ~]

oct/nov 2010 varient 32 paper 3
qustion 2 

[Vin]

Can you post a link, please?

[~ Miss Relina ~]

Can you post a link, please?

http://www.xtremepapers.me/CIE/Cambridge%20IGCSE/0625%20-%20Physics/0625_w10_qp_32.pdf
here

[Vin]

http://www.xtremepapers.me/CIE/Cambridge%20IGCSE/0625%20-%20Physics/0625_w10_qp_32.pdf
here

Q 2

a) Ep = mgh = 0.15 * 10 * 0.3
= 0.45 J

b i) Always remember, Kinetic energy of any body is maximum and Potential energy is minimum at the lowest point of its motion. (revise the line)

so the lowest point of the bob is 0.1 m (o.3 - 0.2 i.e height of the bob in fig. and length of the string)
here the kinetic energy is max and p e is min.
always Ep lost = Ek gain
so Ep at this point = 0.15 * 10 * 0.1
= 0.15 J

ii) Ek = 0.5 * m * v^2
0.15 = 0.5 * 0.15 * v^2
v = 1.4 ms-1

iii) 0.3, because the bob has only that much of energy to reach to the other side, energy is not lost or gained during the system. (extra info - Then again a question arises, at the left the length of the string is "more", if you see, at the release point the length of the string is small, so the velocity with which the bob will travel to left is greater, then will slow down, so ultimately both the energies during the motion add up to give the resultant energy of 0.45 J or energy at 0.3 to the right. If you know what I mean )

iv) drawing is easy. they haven't ask you for a precise scale drawing.

[~ Miss Relina ~]

Q 2

a) Ep = mgh = 0.15 * 10 * 0.3
= 0.45 J

b i) Always remember, Kinetic energy of any body is maximum and Potential energy is minimum at the lowest point of its motion. (revise the line)

so the lowest point of the bob is 0.1 m (o.3 - 0.2 i.e height of the bob in fig. and length of the string)
here the kinetic energy is max and p e is min.
always Ep lost = Ek gain
so Ep at this point = 0.15 * 10 * 0.1
= 0.15 J

ii) Ek = 0.5 * m * v^2
0.15 = 0.5 * 0.15 * v^2
v = 1.4 ms-1

iii) 0.3, because the bob has only that much of energy to reach to the other side, energy is not lost or gained during the system. (extra info - Then again a question arises, at the left the length of the string is "more", if you see, at the release point the length of the string is small, so the velocity with which the bob will travel to left is greater, then will slow down, so ultimately both the energies during the motion add up to give the resultant energy of 0.45 J or energy at 0.3 to the right. If you know what I mean )

iv) drawing is easy. they haven't ask you for a precise scale drawing.

Thanks but in b revised the graph and i think it should be   0.2

[Vin]

Thanks but in b revised the graph and i think it should be   0.2

You're right :/

sorry, my bad.
Okay, so 0.1 is the CHANGE in height. It was 0.1 from the peg, now at perpendicular, it is 02. So delta h is 0.1
reason because when it is at the lowest position, there is still some potential energy, so we cannot take that as 0. so we have to consider the change in height, or change in potential energy.

[~ Miss Relina ~]

You're right :/

sorry, my bad.
Okay, so 0.1 is the CHANGE in height. It was 0.1 from the peg, now at perpendicular, it is 02. So delta h is 0.1
reason because when it is at the lowest position, there is still some potential energy, so we cannot take that as 0. so we have to consider the change in height, or change in potential energy.

plz we dont take it as 0. what
and i know that ur convined but my bad the march schme said ur previous answer is right???

[Blizz_rb93]

I need a list of all the precautions in radioactivity
Thank You =D

[SauD~]

I need a list of all the precautions in radioactivity
Thank You =D

Safety Precautions:
• Keep all radioactive materials in sealed containers made
of thick lead.
• Keep as far away from radioactive source as possible
and use tongs.
• Waste radioactive products are either buried
underground or under the sea.
• Keep exposure time as short as possible.
• Don’t eat or drink near a radioactive substance.
• Label radioactive sources with radioactive sign.
• Wear a radioactive badge: Hole to detect alpha,
Aluminum to detect beta, Lead to detect gamma.
• Half-life is not affected by temperature, pressure or
chemical reactions.

Copy pasted from my notes

[NotAbod]

• Waste radioactive products are either buried
underground or under the sea.

That's why sea is polluted and soil is infertile!!
Sea creatures die, and plants/underground organisms die.
Idiots are ruining our planet!!

[SauD~]

That's why sea is polluted and soil is infertile!!
Sea creatures die, and plants/underground organisms die.
Idiots are ruining our planet!!

Then were can we keep?

[NotAbod]

outer space?