2008 'A' Level H2 Physics P2 1(aXi)
Suqgested Solutions
-
Taking downwards as positive
u =0 s=32m a=9.81ms'] y
=.12" g 61"32
=
25
1rn
sl
1(aXii)
34msl Vv= 25 sine
1
=ii l 34
e=
, ',
1(b)
47.6" dD
dt dv dt = 0.'130 x = 4.38 N
1(c)
34-20 0.95
lf a large splash is created, signiflcant proportion of The terminal velacity which energy possessed by the stone wi be transferred to the stone will rcach is the kinetjc energy and potential energy of the water (also Iowest constant velocitv. as sound). unlike an object This .. rernainlng energy of stone upon entering the sea drcpped from a height, which also attain teminal will be reduced (i.e. slowed down in a shorter velocity. this case, the distance) terminal velocity is the hiqhest constant velocitv.
is
will
2(al
For SHM, a .r
-r,-r2x,
where
c0
is a constant.
Since graph is a straight line with a negative gradient, and it also passes through the origin, the osc .alions o' lhe plate a'e simple
1Jl-a!le
ln
'Directly ptopotlional' is only used when the straight line passes thtough the arigin.
lf the straight line l'a mo'r'c
has a constant qradient but does not
pass through the oigin, we say that it is 'prapoftional'. 2(bxi)
9.81 m
s',
downwards.
This loss of contact will take place when the plate nloves downwards frorn maximum displacement (where acceleration is a maximum).
When downwards acceleration of the plate is greater than that of free fall, the normal contact force on the sand will be zero.
2(bxii) 3(aXi)
3.8 mm
Centripetal force
is
provided by the gravitational
force.
GMm
mv2
that centripetal force is the resultant force that acts tawards the centre of the circulat motion! Remember
,'r GMm _ mv2
2t2
Glvlm
2t 3(aXii)
gravitational potential energy = -
GMm
r GMm
gravitational potential energy kinetic
energy
, =-GMm
=_2
2t 3(bxi)
Use rclatianship in deuved tn (a)(ii) lo plot out 4 sels Note that if gtidlines are given, al coatdtndles tRp.5O ' 1ae). (2Rp.2.5 x 10"). l3Rp you are expected ta do an accurate plot. 1 4 \ 1O') and (4Ra. 1.3 / 10') Then draw the hest fit curve.
lf only a sketch is required, you willjust be given axes. ln doing gtaph work, always remember to label the axes and possible intercepts.
2lP?rge
Please do nat be mistaken
3(bxii)
that:
KE-125x10eJ 1.".|-u,2 =1 25,16s 2x1 25xfie
^KE=%m(^vf!!!
= 1250 m s_r
Obviously, 1v, vS'? + 1v.1'z- 1v)')
When R = 2Rp,
KE=25x1OeJ
...1^u.z =2.5r1gn 2x 2.5x 1oe 1600
=1768ms1
change ln velocity = 1768 - 1250 = 518 m s-1
maxP=5.62W
4(aXi)
Since P =lV,
y=9J4=125a 45
4(aXii)
5.62=1.252R
R=3.60O This question preseDts 2 sels boundary conditiotis. A typical method of solving such questions involves forming 2 simultaneous equations and solving them! Simple as that!
E=lR+lr
4(b)
of
E = (1 25)(3 60) + (1.2s)r E = (1 60X2 03) + (1.60)r
E=3.25+1.6t
---
,(2)
(1)=\2): 4 5+125r
=3.25 + 1.6r
|=
1)q :a:
0.35
=357A
You might have naticed that the maximum powet theorcm also predicts that the internal reslsiarce ls 3.60 O.
Hawever, you cannot quote
the theorem because the questian specified the approach you shauld take.
ln any case, knowledge of this theorem can help you verify that your answer is coffect.
3|
f--'
ir
.j
..,
At low temoeratures: Conduction band
At low temperatures (near 0 K), the conduction band is completely empty and ihe valence band is cornp etely filled because the electrons in the valence
band do not have sufficient energy to jump ihe energy gap
(:
1 eV)
When a potentia difFerence is applied across the semiconductor, there does not have significant amounts of charge carrierc to conduct eiectricity. Hence its resistance is very high.
At hiqher temperatures:
conduction band Valence band raom temperature (a few Kelvins), the hundred be thermally electrons excited inta the conduction band.
At higher temperatures some of the electrons will At gain suffioient energy to overcome the small energy gap and migrate to the conduction band, leaving behind holes.
When a potentjal difference is applied across the semiconductor. the electrons and holes act as charge carriers and contribute io the current. This increase in charge carriers reduces the resistance of the semiconducior. 6(a)
Ability of the nucleus to decay,
in the process emit cr, Il
particles or y-radiation
spontaneoLrsly.
6(bxi)
Tl.e p'obabrlity lhat a nucleJs will decay per unit time.
4ll'ig.
wi
6(bxii)
A=1.26x1058q
) anx 1n 11 '", No of nuclides N = q-'* 1
26'10:.
N 1606x'1ora ^=4= 6(c)
-
=
1.606r t0 "
-785,1oiosr
l" is
smalt, activity would not change while rnass and activity are being appreciably
When
measured, hence giving a more accurate value. 7(aXi)
At the start of the explosion, the rate of increase of Rate of increase of radius is given by the gradient of the radius with time was large. qraph.
The rate of increase of radius with time gradually decreases as time passes.
When doing graph wark, have 'qrcdient' and 'area under
at the back of your minds. These 2 quantities graph'
usually have some PhYsical siqnificance.
7(aXii)
In a room of such dimensions, the fireball would have expanded to completely fill the room in a matter of a
A person in the room will not be able to run out in time.
7(b)(i)
Coordinate of plat = (1.6, lg 14.5)
When drawing best fit lines in are expected to rccall what You Iearnt in SPA.
witten papers, you
Markers will be looking out for Iines/cuNes which are close
to the
plotted points, with
equal disttibution
of
plots
around the Iines/cuNes.
7(bxii)
Gradient of line = 0.4
Show working using your drawn line. When choosing coordinates of triangle to calculate gradient, ensure that is large.
you triangle
Coordinates chosen should lie on the best fit line.
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Note the command word
7(bxiiD
nlogR=logk+mlogt
'suggestl
m
Any
= gradrent ot lrne
n
-
reasonable/sensible answer can be given crcdit.
Since m and n are integers, possible values are:
m=2,n-5 m
=4,n
=10
etc.
Such a technique has been tested as 'A' level a couple of times in recent years.
7(c) R5
For each value of V, determine the corresponding R. Then calculate the value of
I.
V
Within limits, the values should be constant.
7(dxi)
Anything sensible that is prapefty of fuel. e.g. calorific value of the fuel
7(dxiD
Anything sensible. e.g. fuel thank of a car
6lPage
