TYS 'O' LVL physic questions
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Originally posted by eagle:
MJ is mega joules
it is 10^6 joules
so 1.04 * 10^6 J = 1040000 J
am i suppose to understand MJ at O lvl standard? -
Originally posted by gunner77:
the answer is "they have different wavelengths"i don understand.
what you have learned is speed of all electromagnetic waves is a constant
so the thing that varies is either frequency or wavelengths since v = fλ is a constant
Example, gamma rays have higher frequencies (and thus shorter wavelengths) than visible light.
Radio waves have lower frequencies (and thus longer wavelengths) than X-rays
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Originally posted by eagle:
what you have learned is speed of all electromagnetic waves is a constant
so the thing that varies is either frequency or wavelengths since v = fλ is a constant
Example, gamma rays have higher frequencies (and thus shorter wavelengths) than visible light.
Radio waves have lower frequencies (and thus longer wavelengths) than X-rays
ya thanks i understand liao
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Originally posted by gunner77:
am i suppose to understand MJ at O lvl standard?yes
kilo (k)
mega (M)
giga (G)
tera (T)milli (m)
micro (μ)
nano (n)
pico (p)you can remember the top 4 in terms of your computer data size, i.e.
kilobyte
megabyte
gigabyte
terabyte -
ok thanks
one more question pls
Two plastic rods repel each other after they have been rubbed with a cloth.
a) suggest why the plastic rods repel each other?
b) a glass rod is rubbed with a cloth. this glass rod then attracts the plastic rods (a).
suggest why the glass rod attracts the plastic rods?
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a) After being rubbed with the cloth, both rods are equally charged. Because like charges repel, the plastic rods repel each other..
b) I suppose for this you would actually have to know the charge that each rod is after being rubbed... so I'll leave it to someone else. -_- -
Originally posted by Zandermccoll:
a) After being rubbed with the cloth, both rods are equally charged. Because like charges repel, the plastic rods repel each other..
b) I suppose for this you would actually have to know the charge that each rod is after being rubbed... so I'll leave it to someone else. -_-
ohh thanks for the part (a)now i understand thanks!
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dun really need to know what and which charges
but from the question, you can safely answer that it is because the glass rod has the opposite charge as the plastic rod, and since opposite charges attract, the glass rod attracts the plastic rods
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Originally posted by eagle:
dun really need to know what and which charges
but from the question, you can safely answer that it is because the glass rod has the opposite charge as the plastic rod, and since opposite charges attract, the glass rod attracts the plastic rods
ohh ok thanks !
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i have one more question
A beaker can hold 250cm^3 of liquid. when its filled with paraffin ( density 0.80g/cm^3), the total weight is 2.6N. Assume g=10N/kg
a) calculate the mass of paraffin in the beaker.
b) calculate the mass of the beaker.
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a) mass = 250 * 0.8 = 200 g
b) mass of beaker = (2.6 / 10 * 1000) - 200 = 60 g
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Originally posted by eagle:
a) mass = 250 * 0.8 = 200 g
b) mass of beaker = (2.6 / 10 * 1000) - 200 = 60 g
err i don understand part Bcan u explain?
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which part of the solution not clear? all of it? cannot be right?
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Originally posted by skythewood:
which part of the solution not clear? all of it? cannot be right?
why he 10 x 1000 ?
why must x 1000?
the formula is W = mxg
2.6 = M x 10
M = 2.6/10 = 0.26 mah?
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other than the 1000, the rest is ok right?
the 1000 is convert kg to grams.
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Originally posted by skythewood:
other than the 1000, the rest is ok right?
the 1000 is convert kg to grams.
the rest is okhow to tell its in kg?
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look at the units in the question.
==> g=10N/kg
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Originally posted by skythewood:
look at the units in the question.
==> g=10N/kg
ohh, in that casemay i ask, is it always N/kg?
or is there something as N/g ?
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i never see N/g before. can be done, but i never seen it before.
kg is the SI unit for mass.
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Originally posted by skythewood:
i never see N/g before. can be done, but i never seen it before.
kg is the SI unit for mass.
ok thanks alot man !even though its a 1 mark question thanks for clarifying my doubts
thanks to eagle too
thank you everyone
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hey guys i need help in these 2 questions
4b) describe the energy change which takes place as the pendulum comes to rest.
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a large box of mass 50kg rests on a horizontal floor. a man moves the box by pushing it with a horizontal force of 200N. the box moves at a constant speed of 0.25m/s.
A) calculate the word done on the box each second by the man.
B) state the rate at which work is done on the box, i.e the power.
C) (i) state the value of the force of friction between the floor and the box.
(ii) explain ur answer
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let's say pendulum swing from left to right.
left have max P.E. mid point max K.E. right has Max P.E.
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Originally posted by skythewood:
let's say pendulum swing from left to right.
left have max P.E. mid point max K.E. right has Max P.E.
but the answer sheet write " as the pendulum comes to rest, the potential energy and kinetic energy is converted to heat energy in overcoming air resistance. "how come got heat energy?
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Originally posted by gunner77:
a large box of mass 50kg rests on a horizontal floor. a man moves the box by pushing it with a horizontal force of 200N. the box moves at a constant speed of 0.25m/s.
A) calculate the word done on the box each second by the man.
B) state the rate at which work is done on the box, i.e the power.
C) (i) state the value of the force of friction between the floor and the box.
(ii) explain ur answer
A) work done = force x distance
work done per second = force x distanced moved per secondB) power = work done per second. same as A
C) i) horizontal force (200) = work done + friction
ii) since the box is not accelerating, net force = ma, net force = 0. so refer to above equation.