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Ans is D, Because:
Ans is D, Because:
^R/R = ^I/I + ^V/V----- ^= Delta
R=V/I
R= 15/2=7.5
SO,
^R/R=^I/I+^V/V
^R=(^I/I+^V/V)R
^R=(0.2/2 + 0.5/15)*7.5 = 2
It's D.
The uncertainty in R can find by first finding the fractional uncertainties of I and V, and then adding them and multiplying by the the value of resistance calculated.
( 0.2/2 + 0.5/15 ) * 7.5
= -+1 ohm
In this question we're told that the velocity is positive upwards. Also, we know that at highest & lowest points the mass will come momentarily to rest. So when mass is at lowest point, the velocity will be zero, and afterwards, when it'll again start moving upwards, it's velocity will be positive. this elimintes the chance of B being the answer as after coming to rest, the velocity is negative showing that the ball is moving downwards now.View attachment 58723
can someone tell me why the ans isnt B???! :'(
So is C the ans?In this question we're told that the velocity is positive upwards. Also, we know that at highest & lowest points the mass will come momentarily to rest. So when mass is at lowest point, the velocity will be zero, and afterwards, when it'll again start moving upwards, it's velocity will be positive. this elimintes the chance of B being the answer as after coming to rest, the velocity is negative showing that the ball is moving downwards now.
Hope you understood.
No. As I explained above, it'll be mometarily at rest at lowest point, so it's velocity will be zero there. So it can't be C.So is C the ans?
In this question we're told that the velocity is positive upwards. Also, we know that at highest & lowest points the mass will come momentarily to rest. So when mass is at lowest point, the velocity will be zero, and afterwards, when it'll again start moving upwards, it's velocity will be positive. this elimintes the chance of B being the answer as after coming to rest, the velocity is negative showing that the ball is moving downwards now.
Hope you understood.
Let m√2gh1 = V1 and -m√2gh2= V2View attachment 58724
and why is this B not A?? when it changes direction isnt it supposed to be subtracted?
Sorry for getting late.View attachment 58724
and why is this B not A?? when it changes direction isnt it supposed to be subtracted?
Let m√2gh1 = V1 and -m√2gh2= V2
So change in momentum will be,
V1-V2
which is equal to
m√2gh1-(-m√2gh2)
so,
m√2gh1+m√2gh2
is the ans.
Hope u got that
Sorry for getting late.
Look, if you take the downward direction to be negative, and the upward direction to be positive, then the momentum before collision will be : -m√(2gh1)
and the collision after collision will be m√(2gh2)
so then the change in momentum can be found by:
final momentum - initial momentum
= m√(2gh2) - (-m√(2gh1))
= m√(2gh2) + m√(2gh1))
So Answer is B.
P.S. You can also take the upward direction to be -ive and downward direction to be +ive, but this will result in the change in momentum to be :
- m√(2gh2) - m√(2gh1)) <--- this will be also correct, but this not an option given here.
Anyways, this question was solved by myself.
u = 1.66 x 10^-27http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_w12_qp_43.pdf question 1bii) HELP PLEASE! I don't understand how they got mass as 1.66x10^-7 (other than that I understand everything) thanks a lot in advance!
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