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Unformatted text preview: N01/430/S(2) INTERNATIONAL BACCALAUREATE
BACCALAURÉAT INTERNATIONAL
BACHILLERATO INTERNACIONAL Name PHYSICS
STANDARD LEVEL
PAPER 2 Number
Monday 19 November 2001 (afternoon)
1 hour INSTRUCTIONS TO CANDIDATES
!
!
!
!
! Write your candidate name and number in the boxes above.
Do not open this examination paper until instructed to do so.
Section A: Answer all of Section A in the spaces provided.
Section B: Answer one question from Section B in the spaces provided.
At the end of the examination, indicate the number of the Section B question answered in the
box below. QUESTIONS ANSWERED EXAMINER SECTION A ALL SECTION B ......... TEAM LEADER
/25 /25 /25 /25 /25 /25 TOTAL TOTAL
/50 881180 IBCA TOTAL
/50 /50 20 pages –2– N01/430/S(2) SECTION A
Candidates must answer all questions in the spaces provided.
A1. This question is about power dissipation in a resistor and the internal resistance of a battery.
In the circuit below the variable resistor can be adjusted to have known values of resistance R. The
battery has an unknown internal resistance r.
r
–––– I A
R The table below shows the recorded value I of the current in the circuit for different values of R.
The last column gives the calculated value of the power P dissipated in the resistor.
R/!
0
1.0
2.0
3.0
4.0
6.0
8.0
10.0
(a) I/A
!0.01 A
1.50
1.20
1.00
0.86
0.75
0.60
0.50
0.43 P/W
0
1.4
2.0
2.2
2.3
2.2
2.0 Complete the last line of the table by calculating the power dissipated in the variable resistor
when its value is 10.0 !. [2] .........................................................................
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......................................................................... (This question continues on the following page) 881180 –3– N01/430/S(2) (Question A1 continued)
(b) If each value of R is known to !10 % determine the absolute uncertainty in the value of P
when R = 10.0 !. [3] .........................................................................
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(c) On the grid below plot a graph of power P against resistance R. (Do not include error bars). [4] (d) It can be shown that the power dissipated in the external resistor is a maximum when
the value of its resistance R is equal to the value of the internal resistance r of the battery
i.e. R = r. Use this information and your graph to find the value of r. [1] .........................................................................
(e) The manufacturer of the battery gives the value of its internal resistance as 4.50 ! ! 0.01 !.
Is the value of r that you obtained from your graph consistent with the manufacturer’s value?
Explain. [2] .........................................................................
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881180 Turn over –4– N01/430/S(2) A2. This question is about a bouncing ball and contact time. Metre rule Ball Top pan balance
Miguel has devised a method to measure how long a bouncing ball is in contact with the surface
from which it bounces. The method consists of dropping the ball on to the scale pan of a top pan
balance as shown in the diagram above. The balance is calibrated in newtons and Miguel records
the maximum reading on the scale, the height from which the ball is dropped and the height to
which it bounces.
Miguel obtains the following information.
Height from which the ball is dropped = 0.80 m
Height to which the ball bounces
= 0.60 m
Maximum reading on the balance scale = 50.0 N
The mass of the ball is 0.20 kg and the acceleration due to gravity is taken to have a value of 10 m s −2 .
(a) Calculate
(i) the speed of the ball when it strikes the scale pan. [1] .....................................................................
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(ii) the speed of the ball when it leaves the scale pan. [1] .....................................................................
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(iii) the total change in momentum of the ball between striking and leaving the scale pan. [2] .....................................................................
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(This question continues on the following page)
881180 –5– N01/430/S(2) (Question A2 continued)
(b) Miguel assumes that the contact force between the ball and the scale pan varies with time as
shown below.
Force / N
50 – – – – – – – – – – – – – – – – – – – Contact time "t
(i) Time / s What does the area under the graph represent? [1] .....................................................................
(ii) Calculate the contact time "t. [2] .....................................................................
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(c) 881180 Miguel now drops another ball from the same height on to the scale pan. This ball is the
same mass as the first ball but is made of a harder material. Sketch, using the same axes as
in (b) above, the shape of the graph Miguel might expect to get for this ball. [2] Turn over –6– N01/430/S(2) A3. This question is about using the radioactive decay law to determine the age of an ancient campsite.
(a) The radioactive isotope carbon 14 (C14) is continually being produced in the upper
atmosphere by the interaction of neutrons with nitrogen 14.
Complete the nuclear reaction equation below for the formation of C14.
14
7 (b) N + n = 14 C +
6 [1] Some of the carbon atoms in a living tree consist of the radioactive isotope C14. Due to the
continual taking in of carbon the amount of C14 in the living tree remains constant
throughout the life of the tree. When the tree dies the taking in of carbon ceases and the
amount of C14 in the tree decreases with time.
(i) Explain why the amount of C14 decreases with time. [1] .....................................................................
.....................................................................
(ii) The halflife of C14 is 5600 years and the activity of wood from a living tree is
16.8 disintegrations per minute per unit mass.
A piece of burnt wood (charcoal) found at an ancient settlement has an activity of
4.2 disintegrations per minute per unit mass. Estimate the age of the settlement.
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..................................................................... 881180 [2] –7– N01/430/S(2) Blank page 881180 Turn over –8– N01/430/S(2) SECTION B
This section consists of three questions: B1 (parts 1 and 2), B2 and B3. Answer one question in this section.
B1. This question is in two parts. Part 1 is about change of phase, specific heat capacity and thermal
energy transfer and Part 2 is about the motion of charged particles in electric and magnetic fields.
Part 1. Change of phase, specific heat capacity and thermal energy transfer.
(a) In order to keep a liquid boiling, energy must be continually supplied to it. While the liquid
is boiling its temperature remains constant. Explain what must be happening to the kinetic
energy and the potential energy of the molecules of the liquid while it is boiling. [2] .........................................................................
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(b) In an attempt to measure the power supplied by a domestic gas burner a measured mass of
water in an aluminium saucepan was heated by the burner until boiling. At this point a
stopwatch was started and the water boiled for a measured interval of time. After this time
interval the saucepan was removed from the burner and the mass of the saucepan plus water
was recorded. Water Saucepan Burner
The following data is available:
Mass of empty saucepan
Mass of water plus saucepan at start
Mass of water plus saucepan after boiling has taken place
Time for which the water is boiled
Latent heat of vaporisation of water
Specific heat of water =
=
=
=
=
= 250 g
1250 g
850 g
15 min (900 s)
2.3 × 106 J kg −1
4200 J kg −1 K −1 (This question continues on the following page)
881180 –9– N01/430/S(2) (Question B1 part 1 continued)
(i) What mass of water is boiled away in 15 min? [1] .....................................................................
(ii) How much energy is required to boil away this mass of water? [2] .....................................................................
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(iii) Show that thermal energy is supplied to the saucepan and the water at a rate of 1000 W. [2] .....................................................................
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(iv) Explain why the rate at which energy is supplied by the burner will actually be greater
than 1000 W. [1] .....................................................................
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(c) Use the additional data given below to show that the temperature of the lower surface of the
base of the saucepan (labelled A in the diagram) is only about 0.6 ! C higher than that of the
temperature of the boiling water. Water
A Burner
Data:
Thermal conductivity of aluminium = 200 W m −1 K −1
Area of the saucepan base
= 5.0 × 10−2 m 2
Thickness of the saucepan base
= 6.0 mm [3] .........................................................................
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(This question continues on the following page)
881180 Turn over – 10 – N01/430/S(2) (Question B1 part 1 continued)
(d) The actual temperature of the burner is about 600 ! C . Suggest why the lower surface of the
base of the saucepan is not at the same temperature as the burner. [2] .........................................................................
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(e) Another experiment is now carried out in order to measure the specific heat of aluminium in
which a measured mass of cold water is heated in the saucepan to a temperature of 90 !C .
Assuming that the burner supplies energy at the rate of 1000 W to the water, use the data
below to determine a value for the specific heat of aluminium.
Mass of empty saucepan
Mass of saucepan plus water
Initial temperature of the water
Final temperature of the water
Time for the water to reach final temperature
Specific heat of water =
=
=
=
=
= 250 g
1250 g
20 !C
90 !C
315 s
4200 J kg −1 K −1 [4] .........................................................................
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......................................................................... (This question continues on the following page) 881180 – 11 – N01/430/S(2) (Question B1 continued)
Part 2. Motion of charged particles in electric and magnetic fields.
In the diagram below a positive ion of charge + q moving with speed v enters a region in which
there is a uniform electric field of strength E and a uniform magnetic field of strength B. The
magnetic field is directed into the plane of the paper and the electric field is parallel to the plane of
the paper as shown below.
Region of fields
x Magnetic field B into
plane of paper x x
ion
x x x Electric field E x x x x x x x x
v x
x x x x x x x x x x x x x x E
(a) Show on the diagram the directions of the electric force and magnetic force acting on the ion. (b) Write down an expression for
(i) the electric force acting on the particle. [2] [1] .....................................................................
(ii) the magnetic force on the particle. [1] ..................................................................... (c) Show that if the particle travels without deflection through the fields then
v= E
B [2] .........................................................................
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(This question continues on the following page)
881180 Turn over – 12 – N01/430/S(2) (Question B1 part 2 continued)
(d) The electric field is now switched off and an identical ion travelling with speed v enters the
region of magnetic field as shown below.
x x x x x x x x x x x vx x x x x x x ion x x x x x x Explain why the ion will describe a circular path in the region of the magnetic field.
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......................................................................... 881180 [2] – 13 – N01/430/S(2) Blank page 881180 Turn over – 14 – N01/430/S(2) B2. This question is about waves and their various properties.
Diagram 1 below represents a snapshot of some of the wavefronts of a continuous plane wave
travelling in the direction shown.
Diagram 2 is a sketchgraph that shows how the displacement of the medium through which the
wave is travelling varies with distance along the medium.
Diagram 1
Direction of travel Displacement of the medium Diagram 2 Zero
displacement Distance along the medium
The frequency of the source producing the waves is 10 Hz and the speed of the waves is 30 cm s −1 .
(a) On Diagram 1 mark the wavelength of the waves. [1] (b) Calculate the value of the wavelength of the waves. [1] .........................................................................
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(c) Another snapshot of the wave is taken 0.05 s later.
(i) Determine how far the wavefronts have moved in this time. [2] .....................................................................
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(ii) On Diagram 2 sketch another graph to show how the displacement of the medium now
varies with distance along the medium. [1] (This question continues on the following page)
881180 – 15 – N01/430/S(2) (Question B2 continued)
Parts (d) and (e) deal with the reflection and refraction of waves.
(d) !
The same wavefronts as in Diagram 1 are now incident at an angle of 45 to a boundary from
which they are reflected. On the diagram below sketch the position of the wavefront labelled AB
when the point B on the wavefront has just reached the boundary. Direction of travel B A 45! (e) [1] Boundary The same waves now travel across a boundary between two different media. The diagram
below shows wavefronts incident on this boundary such that they make an angle of 55! with
the normal. The speed of the waves in medium 1 is 30 cm s −1 and in medium 2 is 45 cm s −1 .
(iii)
Normal
–––––––––––––– Medium 1 Direction of travel 55! Boundary Medium 2
(i) What is the frequency of the waves in medium 2? [1] .....................................................................
(ii) What is the wavelength of the waves in medium 2? [2] .....................................................................
.....................................................................
(iii) On the diagram sketch the position of the wavefront labelled AB when the point B on
the wavefront has just reached the boundary. [2] (This question continues on the following page)
881180 Turn over – 16 – N01/430/S(2) (Question B2 continued)
(iv) Calculate the value of the angle that the wavefronts in medium 2 make with the normal. [4] .....................................................................
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(v) !
Explain what will happen to waves in medium 1 that are incident at an angle of 45 to
the normal and justify your explanation by means of a calculation. [4] .....................................................................
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Part (f) deals with the interference of waves.
(f) In the diagram below S1 and S2 are two continuous harmonic sound sources that emit sounds
of identical frequency. The distance S1X = S2 X . An instrument that detects sound intensity
is moved along the line AB. S1 ............................................................................ A ............................................................................ X
S2 B (This question continues on the following page)
881180 – 17 – N01/430/S(2) (Question B2 continued)
(i) On the axes below sketch a graph to show how the intensity of sound varies with
distance along AB. Mark the position of X on your graph. [2] Sound intensity Distance along AB
(ii) Explain what is meant by the principle of superposition as applied to waves and
describe how this principle accounts for the variation of the sound intensity along the
line AB. [4] .....................................................................
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..................................................................... 881180 Turn over – 18 – N01/430/S(2) B3. This question is about the braking distance of a car and the power developed by the car engine.
The minimum braking distance is the shortest distance a car travels without skidding from the
moment the brakes are applied until the moment the car comes to rest
The graph below shows how the minimum braking distance d varies with the initial speed v of a car
travelling along a straight, horizontal road. 300
250
200
d / m 150 100
50
0 0 10 20 30
v / ms (a) 40 50 −1 By choosing two data points show that the graph suggests that the minimum braking distance
depends on the square of the initial speed. [4] .........................................................................
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(b) Explain why, if the braking force is constant, you would expect theoretically the braking
distance to depend on the square of the speed. [3] .........................................................................
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......................................................................... (This question continues on the following page) 881180 – 19 – N01/430/S(2) (Question B3 continued) (c) The car has a mass of 1500 kg and is moving with an initial speed of 20 m s −1 when the
brakes are applied. Calculate
(i) the time that it takes the car to come to rest. [3] .....................................................................
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(ii) the average braking force acting on the car. [3] .....................................................................
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(d) The stopping distance of a car is the distance that the car travels in coming to rest from the
moment that the driver decides to apply the brakes. The stopping distance is greater than
the minimum braking distance. Explain why you think that this is so. [2] .........................................................................
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(e) Using the same axes as for the graph given at the start of the question sketch a graph to show
how the stopping distance varies with initial speed. Explain the shape of the graph that you
have drawn. [3] .........................................................................
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......................................................................... (This question continues on the following page) 881180 Turn over – 20 – N01/430/S(2) (Question B3 continued) (f) If the car were travelling down an incline would you expect the minimum braking distance
for a given initial speed to be greater than or less than the braking distance on the level for the
same road conditions? Explain. [2] .........................................................................
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The next part of the question looks at the power developed by the car engine.
(g) Travelling at a constant speed of 40 m s −1 the car engine uses 1 litre of fuel for every 12 km
travelled. At what rate does the engine use fuel? [2] .........................................................................
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(h) The combustion of 1 litre of fuel releases 35 MJ of energy and at a speed of 40 m s −1 the car
engine is 25 % efficient. Determine the power output of the car engine at this speed? [2] .........................................................................
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(i) Use your answer to (h) above to estimate the average drag force acting on the car when travelling
at a constant speed of 40 m s −1 .
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......................................................................... 881180 [1] ...
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This note was uploaded on 09/30/2011 for the course CHEM 102 taught by Professor Tina during the Spring '11 term at Global.
 Spring '11
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