WESTMINSTER SCHOOL
THE CHALLENGE 2013
PHYSICS
Thursday 2 May 2013
Time allowed: 30 minutes
Please write in black or blue ink.
Write your answers in the spaces provided.
For examiner use only
Total
Mark
P1 (Multiple Choice – 10 marks)
Choose A,B,C,D or E for each of the following questions.
a) Which of these values is an appropriate estimate of the weight of a car?
A: 500 kg
B: 1000 kg
C: 50000 g
D: 20000 N
E: 9000 lb
b) An ostrich runs along a road at 12 km/h. After 15 minutes it has travelled
A: 18 km
B: 180 km
C: 1800 m
D: 3000 m
E: 30 km
c) A clear plastic bottle is washed out with boiling water, and the lid replaced tightly. After
10 minutes it is noticed that the bottle has been squashed inwards in the middle. What is the
most likely cause of the change of shape of the bottle?
A: The plastic was weakened
B: The bottle was empty
C: The plastic warmed up and expanded
D: Atmospheric pressure increased
E: The pressure inside the bottle decreased.
d) A lump of ice at 0 degrees Celsius is placed in a glass of lemonade at 10 degrees Celsius.
The resulting glass is placed in a room at 20 degrees Celsius.
Here are 3 statements
(i) The ice gains energy from the lemonade
(ii) The room gains energy from the lemonade
(iii) After a long time the lemonade will have a temperature of 20 degrees Celsius
Which of these statements is/are true?
A: (i) only
B: (ii) only
C: (iii) only
D: (i) and (ii)
E: (i) and( iii)
e) Which particles are in the nucleus of an atom?
A: Neutrons and Electrons
B: Neutrons and Protons
C: Protons and Electrons
D: Neutrons only
E: Electrons only
f) Which of the following astronomical objects produces its own light?
A: Jupiter
B: A meteor passing through the atmosphere
C: Io (a moon of Jupiter)
D: An asteroid E: None of these
g) A girl is on a train travelling at a steady speed of 10 m/s. She stands on a mark on the
floor. She jumps upwards and reaches her maximum height in 0.2 s. Where does she land?
A: 1m behind the mark
B: 2m behind the mark
C: On the mark
D: 2m ahead of the mark
E: 1m ahead of the mark
h) A spring is compressed by a weight to a length of 24 cm. Two identical such springs side
by side are then each compressed to a length of 32 cm by the same weight. What is the
uncompressed length of one spring?
A: 38 cm
B: 40 cm
C: 42 cm
D: 48 cm
E: 64 cm
Please turn over
i) Which of the following statements is correct?
A: The molecules in ice are bigger than the molecules in steam
B: The molecules in ice are smaller than the molecules in steam
C: The molecules in ice are much closer together than the molecules in steam
D: The molecules in ice are heavier than the molecules in steam
E: The molecules in ice are not moving, but those in steam are.
j) Which of the following has a volume of 10cm3?
A: A rectangular box of dimensions 0.2m x 100mm x 0.5m
B: A rectangular box of dimensions 0.5cm x 0.2m x 10mm
C: A rectangular box of dimensions 10cm x 10cm x 10cm
D: A rectangular box of dimensions 10mm x 1cm x 10m
E: rectangular box of dimensions 0.02m x 2.0 cm x 0.25m
Short answer Questions
P2
Comet ISON was recently identified, and in 2013 will be an impressive temporary addition
to the night sky. It will become visible to the naked eye by late October or early November
and remain so until mid-January 2014, at some points possibly being brighter than the
Moon. Here is a recent image of it, still some distance away:
A comet is a frozen lump of ice and dust. In this case its radius is (currently) estimated to be
around 5km, and it is currently moving at approx 40000 mph!
a) Assuming it has a density of 1000 kg/m3 (the density of water) and is a spherical shape,
calculate an approximate value of:
4
i) Its volume [Hint: The volume of a sphere is 3 𝜋𝑟 3 ]
[3]
ii) Its mass
[2]
Please turn over
b) Here is a diagram showing the eccentric (elongated) orbit of the comet:
i)
Its perihelion (the point at which it is closest to the Sun) will occur in late
November 2013. At this point what can you say about the speed of the comet
relative to its speed now?
[1]
ii)
Why is the tail of the comet not behind it (ie in the opposite direction to its
motion)?
[1]
P3
Galileo noticed that the time it took a pendulum to perform one complete oscillation (ie to
swing across and back) was not dependent on the height that it was swung from. In fact
neither does it depend on the mass of the bob at the end of the string. For a simple mass
swinging on the end of a string of length L, the time taken to complete one complete
oscillation is
𝑇 = 2𝜋√
𝐿
𝑔
Where L is the length of the pendulum IN METRES, and g is the gravitational field strength,
which on Earth is 10 N/kg. (NB IT IS NOT NECESSARY TO HAVE SEEN THIS
EQUATION BEFORE)
a) Calculate how long it would take a pendulum of length 80cm to perform one complete
oscillation.
[3]
b) If the length of the string was increased by a factor of 4, how would the time for one
oscillation change?
[1]
Please turn over
c) If the same pendulum were to be used on the Moon, how would the time for one
oscillation change?
[1]
P4
Three rock stars named Phil, Mike and Tony are discussing the pressure they exert on the
ground.
Phil: “I have a mass of 50 kg, and my feet have an area of 500 cm2”
Mike: “My feet have an area of 20% more than Phil, and I weigh 20% less than Tony”
Tony: ”The pressure I exert on the ground is 1.5 N/cm2, and my feet have an area of 400 cm2”
NB On the Earth each kg of mass has a weight of 10N
Fill in the gaps in this table:
Name
Weight (N)
Area of feet (cm2)
Pressure on Ground
(N/cm2)
Phil
500
Mike
Tony
400
1.5
[6]
P5 Electricity
a) Draw a circuit with 2 lamps (labelled A and B) connected in parallel to a battery, and 2
switches that can turn the lamps on and off independently.
[2]
b) If lamp A is brighter than the lamp B, what can you say about the current through each
lamp in this parallel circuit?
[1]
c) If the same two lamps were arranged in a series circuit, what could you say about the
current through each lamp?
[1]
d) Which lamp (if either) would be brighter in a series circuit?
[1]
End of paper