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Physics: Post your doubts here!

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hassankhan

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Kindly someone help me with these questions:
Q1) A particle of charge + 2 micro coulomb is placed between two parallel plates , 10 cm apart and with a p.d of 5 kV between them. Calculate the force exerted on the charge.

Q2) A car battery is labelled '50Ah'.This means that it can supply a current of 50 A for one hour.
a) For how long could the battery supply a continuous current of 200 A needed to start the car.

Q3) Calculate the no. of protons which would have a charge of one columb
(Proton Charge= +1.6*10^-19C)
Thanks in advance
 
Dug

Dug

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hassankhan said:
Kindly someone help me with these questions:
Q1) A particle of charge + 2 micro coulomb is placed between two parallel plates , 10 cm apart and with a p.d of 5 kV between them. Calculate the force exerted on the charge.

Q2) A car battery is labelled '50Ah'.This means that it can supply a current of 50 A for one hour.
a) For how long could the battery supply a continuous current of 200 A needed to start the car.

Q3) Calculate the no. of protons which would have a charge of one columb
(Proton Charge= +1.6*10^-19C)
Thanks in advance
Click to expand...
i)
E = F/Q = V/d
F = QV/d

ii)
a) 1Ah = 3600C
50Ah = 3600 x 50 => 180,000C
I = Q/t
t = 180,000/200 = 900s => 0.25h

iii)
1 Proton = 1.6*10^-19C
x Protons = 1C
x = 1/1.6*10^-19 => 6.25*10^18
 
Ali_00921

Ali_00921

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T1sin50° + T2sin40° = 7.5 .. HOW DO I FURTHER SOLVE THIS TO FIND THE VALUE OF T1 AND T2?
 
snowbrood

snowbrood

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Ahmad Zaeem said:
A level ....Physics
M/J 2012 ... P11 ......Q 12, 24 ....PLs Give reasons for answers and the concept!!!...(-_*)

http://papers.xtremepapers.com/CIE/Cambridge International A and AS Level/Physics (9702)/9702_s12_qp_11.pdf
Click to expand...
the distance of block from the level of head of the man is 18m and when to level the head with the block man travels 9m upwards and block 9m downwards.
tension acts towards the pulley and the weight acts opposite to tension i.e downwards.
force acting in the direction of acceleration is considered more in magnitude than the force in opposite direction

for the man
T-80g=80a equation 1
120g-T=120a equation2
adding both equations we get
40g=200a
a=0.2g (given g as 10ms^-2)
a=2ms^-2
v^2=2as (as initial velocity of both the objects is zero )
v^2=2*2*9
v^2=36
v=6ms^-1

for question 24
stress=F/A
F=stress*A
F=(stress/4)*4A (area would be 4A as (2D)^2 is four times greater than (d)^2 for e.g (2*2)^2=16 x(2)^2=4 see
stress should be divided by 4 as the examiner states that load is the same which means the force applied is the same
so to get F 4 must be divided by 4 to get 1 ok!!

stress is directly proportional to strain
so if stress is stress/4 .strain would also be strain/4
stress/4=x/3l.
stress=x/l main formula
coefficient of x would be such that it equals 3/4 because only then we would get our formula u see coefficients will change but the formula wont ok
 
snowbrood

snowbrood

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snowbrood said:
the distance of block from the level of head of the man is 18m and when to level the head with the block man travels 9m upwards and block 9m downwards.
tension acts towards the pulley and the weight acts opposite to tension i.e downwards.
force acting in the direction of acceleration is considered more in magnitude than the force in opposite direction

for the man
T-80g=80a equation 1
120g-T=120a equation2
adding both equations we get
40g=200a
a=0.2g (given g as 10ms^-2)
a=2ms^-2
v^2=2as (as initial velocity of both the objects is zero )
v^2=2*2*9
v^2=36
v=6ms^-1

for question 24
stress=F/A
F=stress*A
F=(stress/4)*4A (area would be 4A as (2D)^2 is four times greater than (d)^2 for e.g (2*2)^2=16 x(2)^2=4 see
stress should be divided by 4 as the examiner states that load is the same which means the force applied is the same
so to get F 4 must be divided by 4 to get 1 ok!!

stress is directly proportional to strain
so if stress is stress/4 .strain would also be strain/4
stress/4=x/3l.
stress=x/l main formula
coefficient of x would be such that it equals 3/4 because only then we would get our formula u see coefficients will change but the formula wont ok
Click to expand...
that mean x=3/4
 
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