The Ultimate Collection of Physics Problems - Space Physics
Contents
Page
SECTION 1 - SIGNALS FROM SPACE
2
Distances in Space
2
Ray Diagrams
3
SECTION 2 - SPACE TRAVEL
5
Weight
5
Weight, Thrust and Acceleration
7
Projectiles
11
Re - Entry
15
SPACE PHYSICS REVISION QUESTIONS
18
General Level
18
Credit Level
19
APPENDIX (I) DATA SHEET
24
APPENDIX (II) ANSWERS TO NUMERICAL PROBLEMS
25
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The Ultimate Collection of Physics Problems - Space Physics
Section 1 - Signals from Space
Distances in Space
In this section you can use the following equation:
v= d
t
where: v = average speed in meters per second (m/s)
d = distance travelled in metres (m)
t = time taken in seconds (s).
Helpful Hint
Because distances in space are so large, astronomers use light years to measure
distance. One light year is the distance light will travel in one year. Light travels at
3 x108 m/s.
1.
How far is a light year?
2.
The star Vega is 27 light years from earth. How far away is Vega in metres?
3.
The star Pollux is 3·78 x1017 m from earth. How far is this in light years?
4.
The star Beta Centauri is 300 light years from earth. How long does it take light to
travel from this star to the earth?
5.
An astronomer on Earth views the planet Pluto through a telescope. Pluto is
5 763 x 106 km from earth. How long did it take for the light from Pluto to reach the
telescope?
6.
Our galaxy, the Milky Way, is approximately 100 000 light years in diameter. How
wide is our galaxy in kilometres?
7.
The nearest star to our solar system is Proxima Centuri which is 3·99 x1016 m away.
How far is this in light years?
8.
Andromeda (M31) is the nearest galaxy to the Milky Way and can just be seen with
the naked eye. Andromeda is 2·1 x 1022 m away from the Milky Way. How long does
it take for light from Andromeda to reach our galaxy?
9.
The Sun is the nearest star to the planet Earth. It takes light 8·3 minutes to reach us
from the Sun. Use this information to find out the distance from the Earth to the Sun
in kilometres?
10. Sir William Herschel, an amateur astronomer, discovered the planet Uranus in March
1781. Uranus is 2 871 x 106 km away from the sun. How long does it take for sunlight
to reach Uranus?
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The Ultimate Collection of Physics Problems - Space Physics
Ray Diagrams
Helpful Hint
You may have noticed that all the images produced by convex lenses in Health Physics
were on the opposite side of the lens from the object. These images are called real
images. Sometimes, however, an image cannot be formed in this way because the rays
spread out after passing through the lens. In this case we must extend the ray lines
backwards until they meet.
Example
image
f
f
object
lens
This type of image, which is formed on the same side of the lens as the object is
called a virtual image.
Remember the rules for drawing ray diagrams:
1. a ray from the tip of the object parallel to the axis passes through the focal point
of the lens.
2. a ray from the tip of the object to middle of the lens continues through the lens in
the same direction.
1.
An object is placed 3 cm from a lens which has a focal length of 2 cm. The object is
1 cm high.
Using a suitable scale, copy and complete the ray diagram below.
(You may find it useful to use graph paper !)
lens
1 cm
high

3 cm
  2 cm
(a) How far from the lens is the image produced?
(b) Is the image inverted or upright?
(c) Is the image real or virtual?
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The Ultimate Collection of Physics Problems - Space Physics
2.
A magnifying glass produces an image which is described as virtual, magnified and
upright.
A 1 cm high object is placed 2 cm from a magnifying lens whose focal length is 3 cm.
(a) Copy and complete the ray diagram below to show how the image is formed.
lens
1 cm
high
 2 cm 
3 cm

(b) Explain why the image is described as virtual, magnified and upright.
3.
A 1 cm high object is placed 5 cm from a lens which has a focal length of 2 cm.
(a) Use a ray diagram to find out what kind of image is formed (i.e. real or virtual?
magnified , diminished or same size? inverted or upright?)
(b) The same object is moved to a distance of 4 cm from the lens. Describe the
image which is now formed.
(You will need to draw a new ray diagram !)
(c) The object is again moved - this time to a distance of 1·5 cm from the lens.
Describe what happens to the image now.
4.
A magnifying glass, which has a focal length of 1 cm, is used to examine some small
objects. Each object is placed 0·5 cm from the lens. By drawing ray diagrams, to an
appropriate scale, find out the size of the image produced by each of the following
objects.
(a) A printed letter which is 4 mm high.
(b) A 2 mm grain of rice.
(c) A 5 mm pearl.
5.
A man creates an image of a fuse using an 8 cm lens. The fuse is 2 cm high and is
positioned at a distance of 4·8 cm from the lens.
(a) Draw a ray diagram in order to find out the height of the image produced.
(b) How far was this image from the lens?
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The Ultimate Collection of Physics Problems - Space Physics
Section 2 - Space Travel
Weight
In this section you can use the equation:
weight = mass x gravitational field strength
also written as
W = mg
where
W = weight in Newtons (N)
m = mass in kilograms (kg)
g = gravitational field strength in Newtons per kilogram (N/kg)
Helpful Hint
On Earth ‘g’ = 10 N/kg but it varies from planet to planet. In questions about weight on other
planets you must use these values by referring to the data sheet on page 24
1.
Find the missing values in the following table.
Mass (kg)
Gravitational field strength (N/kg)
Weight (N)
(a)
12
10
(b)
279
4
(c)
0·56
5·6
(d)
7·89
78·9
(e)
12
700
(f)
10
58
2.
Calculate the weight of a 70 kg man on Earth.
3.
If a moon rock has a weight of 4·6 N, what is its mass?
4.
An objects weight depends on the strength of the gravitational field around it. A
scientist records the weight of a 3 kg rock on each planet and records the information
in the table overleaf.
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Planet
Earth
Jupiter
Mars
Mercury
Neptune
Saturn
Venus
Uranus
Pluto
Weight(N)
30
78
12
12
36
33
27
35·1
12·6
Use the results from the table to work out the value of the gravitational field strength
on each planet ( you can check your answers against the data sheet on page 24).
5.
Using your results to question 4, state which planet(s) have:
(a) the strongest gravitational field strength
(b) the weakest gravitational field strength
(c) a gravitational field strength nearest to that on Earth
(d) a gravitational field strength three times as strong as that on Mercury.
6.
Which is heavier, a 2 kg stone on Neptune or a 0·9 kg rock on Jupiter?
7.
How much lighter does a 65 kg woman seem on the moon, where ‘g’ = 1·6 N/kg, than
on Earth?
8.
Find the weight of a satellite booster on Mars if it weighs 24 N on the moon.
9.
What is the difference in mass between a 40 N weight on Venus and a 104 N weight
on Jupiter?
10. A rock weighs approximately two and a half times its weight on Earth somewhere in
our solar system. Where is it likely to be?
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Weight, Thrust and Acceleration
In this section you can use the equation:
unbalanced force = mass x acceleration
also written as
F = ma
where
F
m
a
= unbalanced force in newtons (N)
= mass in kilograms (kg)
= acceleration in metres per second per second (m/s 2).
Helpful Hint
When a spacecraft is in space the only force acting on it is its engine thrust.
engine thrust (F)
1.
Find the missing values in the table.
Force (N)
2.
Mass (kg)
Acceleration (m/s2)
(a)
700 000
2·0
(b)
45 000
0·9
(c)
1 000
0·05
(d)
3 600 000
0·01
(e)
10 000
80 000
(f)
2 600 000
2 000 000
The engine of a space shuttle can produce a thrust of 600 000 N. The mass of the
shuttle is 8 x 105 kg. Calculate the acceleration of the shuttle in space.
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3.
What engine thrust must be produced by a rocket of mass 3 x 106 kg in order to
produce an acceleration of 1·4 m/s2 in space?
4.
The maximum engine thrust of a spacecraft is 2·4 x 107 N and this produces an
acceleration of 12 m/s2 in space. What is the mass of the spacecraft?
5.
An engine force of 160 kN is used to slow down a shuttle in space. If the mass of the
shuttle is 120 000 kg what is its rate of deceleration?
Helpful Hint
To find the acceleration, a, of an object during a vertical take-off you will need to
calculate the unbalanced force acting on the object first.
thrust
Example
1st.
Unbalanced force = thrust - weight
F
a= m
2nd.
(where F = unbalanced force)
weight
6.
Use the three stages outlined in the example above to find the missing values in the
following table. Assume that each mass is in the Earth’s gravitational field.
Mass (kg)
Weight (N)
Thrust (N)
(a)
3
30
60
(b)
2 000
2 000
21 000
(c)
1 500
20 000
(d)
50 000
550 000
(e)
70 000
840 000
(f)
76 000
896 800
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Unbalanced
force (N)
Acceleration
(m/s2)
8
The Ultimate Collection of Physics Problems - Space Physics
7.
A water rocket has a mass of 0·8 kg and is launched in a school playground with an
initial upwards thrust of 12 N.
(a) What is the weight of the water rocket in the playground?
(b) What is the initial acceleration of the rocket in the
playground?
(c) If this water rocket were launched from the moon, what
would be its initial acceleration?
(Remember to find the new weight first !)
8.
A rocket is launched from Earth with an initial acceleration of 2·5 m/s2. The mass of
the rocket is 1 600 000 kg.
(a) Calculate the unbalanced force acting on the rocket during its launch.
(b) What is the weight of the rocket?
(c) Calculate the engine thrust of the rocket.
(d) What engine thrust would be required to launch this rocket from the moon with
the same acceleration?
9.
Calculate the acceleration of the following objects.
(a) A model rocket of mass 30 kg being launched from Earth with an engine thrust
of 800 N.
(b) A satellite in space whose mass is 1 800 kg and whose engine force is 4·68 kN.
(c) A 100 000 kg shuttle travelling at 50 m/s in space.
(d) A toy rocket of mass 1·5 kg whose engine stopped while the rocket was in mid
air.
(e) A spaceship of mass 4 x 107 kg lifting off from Saturn with an engine thrust of
9 x 108 N.
(f) A rocket of mass 2·2 x 106 kg being launched from Neptune with an engine
thrust of 4·4 x 107 N.
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10. A space shuttle has a weight of 1·8 x 107 N on Earth. Its engines produce a thrust of
2·7 x 106 N during part of its journey through space.
(You will need to refer to the data sheet on page 24 for parts of this question.)
(a) Calculate the mass of the shuttle.
(b) What is the acceleration of the shuttle in space while its engine thrust is
2·7 x 106 N?
(c) Could the shuttle have been launched from Earth with this engine thrust of
2·7 x106 N? Explain your answer.
(d) The engine thrust was 2·7 x 107 N during the launch from Earth. What was the
acceleration of the shuttle during its launch?
(e) If a similar shuttle was launched from Venus with an engine thrust of 2·7 x 107 N,
what would be the acceleration of this shuttle during lift off?
(f) What engine thrust would be required in order to launch this shuttle from Jupiter
with an acceleration of 5 m/s2?
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Projectiles
Helpful Hint
In this section you can make use of the fact that any projectile path can be split into
separate parts - horizontal and vertical.
To solve any projectile problem it is necessary to use the formula which applies to each of
these directions.
Horizontally
Velocity is constant ( a = 0 m/s2)
v= d
t
where
v = average horizontal velocity in metres per second (m/s)
d = horizontal distance travelled in metres (m)
t = time taken in seconds (s).
Vertically
Acceleration due to gravity
a =
where
v-u
t
a = acceleration due to gravity in metres per second per second (m/s 2)
u = initial vertical velocity in metres per second (m/s)
v = final vertical velocity in metres per second (m/s)
t = time taken in seconds (s).
To calculate the vertical distance travelled during any projectile journey you must draw a
speed time graph for the journey and use:
distance travelled = area under speed time graph.
1.
A stone is kicked horizontally at 20 m/s from a cliff top and lands in the water below
2 seconds later.
20 m/s
Calculate :
(a) the horizontal distance travelled by the stone
(b) the final vertical velocity
(c) the vertical height through which the stone drops.
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2.
A parcel is dropped from a plane and follows a projectile path as shown below.
The horizontal velocity of the plane is 100 m/s and the parcel takes 12 seconds to
reach the ground.
100 m/s
Calculate :
(a) the horizontal distance travelled by the parcel
(b) the final vertical velocity of the parcel as it hits the ground
(c) the height from which the parcel was dropped.
3.
Sand bags are released from an air balloon while it is at a fixed height.
The bags follow a projectile path because of strong winds.
30 m/s
The bags have an initial horizontal velocity of 30 m/s and land on
the ground 10 seconds later. Calculate:
(a) the horizontal distance travelled by the sand bags
(b) their final vertical velocity.
4.
A satellite is launched during a practice simulation.
The satellite is given a horizontal velocity of 400 km/s and ‘crashes’ 200 seconds
later.
400 km/s
practise launch pad
Calculate :
(a) the horizontal distance travelled by the satellite
(b) the final vertical velocity of the satellite
(c) the height from which the satellite was launched.
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5.
An archer fires an arrow and aims to hit a target 50 metres away. The arrow is
launched with a horizontal velocity of 100 m/s.
100 m/s
(a) What is the time of flight of the arrow?
(b) Calculate the final vertical velocity of the arrow.
(c) By how much does the arrow miss the target?
6.
A golfer strikes a golf ball and it follows a projectile path as shown below.
(a) What is the vertical velocity of the ball at its maximum height?
(b) What is the horizontal component of the velocity if the ball takes 4 seconds to
travel 400 metres?
7.
While on the moon an astronaut throws a rock upwards and at an angle. The path of
the rock is shown below.
(a) What is the vertical velocity of the rock at its maximum height?
(b) How long does the rock take to reach its maximum height if it has an
initial vertical velocity of 20 m/s?
(Remember! On the moon a = 1·6 m/s 2)
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8.
Part of the space flight of a shuttle is represented in the velocity time graphs below.
(a)
Horizontal motion
(b)
Vertical motion
90
speed
in m/s
40
speed
in m/s
30 time in seconds
30 time in seconds
Use the graphs to find out how far the shuttle travels both horizontally and
vertically in the 30 second journey.
9.
During take off from Mars one of the boosters on a rocket fails causing the rocket to
follow a projectile path rather than a vertical one.
The speed time graphs for a 20 second interval immediately after the booster failed are
shown below.
(a)
speed
in m/s
Horizontal motion
(b)
Vertical motion
speed
in m/s
10
15
20 time in seconds
20
time in seconds
Use the graphs to calculate:
(a) the horizontal distance travelled during take off
(b) the deceleration in the vertical direction during the first 20 seconds
(c) the vertical distance travelled.
10. A stunt motor cyclist tries to beat the record for riding over double decker buses. He
leaves the start position with a horizontal velocity of 35 m/s and lands 2·4 seconds
later. Calculate :
(a) the horizontal distance travelled by the cyclist
(b) the final vertical velocity of the motor cycle as it touches the ground
(c) the height of the platform.
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Re - Entry
In this section you can use all of the following equations:
Ek = 1mv2
2
Eh = cmT
Ew = F x d
where
Ek
Eh
Ew
m
v
c
T
F
d
=
=
=
=
=
=
=
=
=
kinetic energy (J)
heat energy (J)
work done (J)
mass (kg)
speed (m/s)
specific heat capacity (J / kg oC)
change in temperature (oC)
force (N)
distance (m).
Helpful Hint
Energy can not be created or destroyed. It can be changed from one form into another.
When an object re-enters the Earth’s atmosphere it heats up. Some or all of its kinetic
energy changes to heat energy as work is done against friction. The shuttle has heat
resistant tiles covering its body to stop it burning up as it re-enters the atmosphere.
heat resistant tiles
In order to stop the shuttle when it touches down, work must be done by friction
forces in the brakes to change all its kinetic energy into heat energy.
1.
A small piece of metal of mass 2 kg falls from a satellite and re-enters the Earth’s
atmosphere at a speed of 4 000 m/s. If all its kinetic energy changes to heat calculate
how much heat is produced.
2.
How much work must be done by the brakes on a shuttle of mass 2 x106 kg to bring it
to rest if it lands with a touch down speed of 90 m/s?
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3.
The space shuttle Columbia re-entered the Earth’s atmosphere at a speed of
8 000 m/s and was slowed down by friction to a speed of 200 m/s. The shuttle has a
mass of 2 x106 kg.
(a) How much kinetic energy did the shuttle lose?
(b) How much heat energy was produced during this process?
4.
A ‘ shooting star’ is a meteoroid that enters the Earth’s atmosphere and is heated by
the force of friction which causes it to glow. A certain meteoroid has a mass of 30 kg
and enters the atmosphere at a speed of 4 000 m/s. Its specific heat capacity is
600 J /kgoC.
(a) Calculate the heat energy produced when all the meteoroids kinetic energy is
converted to heat.
(b) Calculate the rise in temperature of the meteoroid as it re-enters the atmosphere.
5.
A small spy satellite of mass 70 kg is constructed from a metal alloy of specific heat
capacity 320 J /kgoC. The satellite has a short lifetime of two weeks before it
re-enters the Earth’s atmosphere at a speed of 5 000 m/s.
(a) Calculate how much heat energy is produced when all the satellites kinetic
energy changes to heat energy.
(b) Calculate the theoretical rise in temperature of the satellite .
6.
The nose section of the shuttle is covered with 250 kg of heat resistant tiles which
experience a rise in temperature of 1 400 oC during the shuttle’s journey back through
the Earth’s atmosphere. The shuttle is slowed from 10 000 m/s to 100 m/s during this
part of the journey .
United St
ates
shuttle enters Earth’s
atmosphere
v = 10 000 m/s
United St
ates
v = 100 m/s
(a) How much kinetic energy does the nose of the shuttle lose?
(b) How much heat energy is produced at the nose during re-entry?
(c) Calculate the specific heat capacity of the material used to make the nose tiles.
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7.
A multistage rocket jettisons its third stage fuel tank when it is
empty. The fuel tank is made of aluminium and has a mass of
4 000 kg.
(specific heat capacity of aluminium is 900 J/kgoC)
(a) Calculate the kinetic energy lost by the fuel tank as it
slows down from 5 000 m/s to 1 000 m/s during its journey
through the atmosphere.
(b) How much heat energy is produced?
(c) Calculate the rise in temperature of the fuel tank .
8.
The command module of an Apollo rocket returns to Earth at a speed of 30 km/h.
During its journey through the atmosphere it is slowed to a speed of 10 km/h. The
mass of the module is 2 000 kg .
(a) Calculate the loss in kinetic energy of the command module.
(b) How much work is done by the frictional forces which slowed it down?
9.
Re-entry for a certain shuttle begins 75 miles above the Earth’s surface at a speed of
10 km/s. It is slowed to a speed of 100 m/s by frictional forces during which time it
has covered a distance of 4 x107 m. The mass of the shuttle and its payload is
2·4 x 106 kg.
(a) Calculate the loss in kinetic energy of the shuttle.
(b) How much work is done by friction?
(c) Calculate the average size of the frictional forces exerted by the atmosphere on
the shuttle as it slows down.
10. At touch down a shuttle is travelling at 90 m/s. The brakes apply an average force of
4 x 106 N in total to bring the shuttle to a stand still. The mass of the shuttle is
2 x 106 kg .
(a) How much kinetic energy does the shuttle have at touch down?
(b) How much work must be done by the brakes to stop the shuttle?
(c) Calculate the length of runway required to stop the shuttle.
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Space Physics Revision Questions
General Level
Clues down
Clues across
1.
2.
2.
3.
4.
5.
7.
8.
10.
14.
15.
16.
Jupiter--- Mars are planets.
------- Centauri is the nearest star outwith our
Solar System.
The closest ‘star’ to Earth.
A useful object for star gazing.
We see these because of the different
frequencies in white light.
The moon is a natural satellite of this planet.
This keeps our feet on the ground!
This large lens in a telescope creates the
image of a star.
This quantity is measured in kilograms and
does not change from planet to planet.
700 nm is the wavelength of this light.
The Universe is the name given to --- matter
and space.
4.
6.
8.
9.
11.
12.
13.
17.
18.
This object can separate white light
into its various colours.
We could describe ourselves as this
compared to the Universe.
The number of stars in our Solar
System.
A cluster of stars.
The sun will not keep burning for ----.
Paths for planets around the Sun.
Here the gravitational field strength is
virtually zero.
This fictional character was not from
Earth.!
Obtained by mixing red, green and
blue.
The Sun and its nine planets.
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Credit Level
1.
Stars and galaxies emit radiation at many different frequencies in the electromagnetic
spectrum. By collecting these signals astronomers can learn a lot about our universe.
(a) Copy and complete the diagram of the electromagnetic spectrum shown below.
Gamma
rays
UV
IR
TV
waves
(b) Which waves have the longest wavelength?
(c) It takes radio waves from the galaxy Andromeda 22 million years to reach us.
How far away is Andromeda in kilometres? (one year = 365 days)
(d) Name a detector for each type of electromagnetic radiation in the spectrum.
Light gathered from the stars can be split into spectra using a prism or a diffraction
grating. This allows astronomers to gather a great deal of information about the stars.
(e) What is the name given to the type of spectrum shown below?
(f) Identify two elements present in this spectrum using the information below.
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2.
A magnifying glass, of focal length 5 cm, produces an image of an object.
The object is 3 cm high and is placed 2 cm from the magnifying glass.
(a) Draw a ray diagram to illustrate how the image is formed by the magnifying
glass.
(b) What size is the image produced by the lens?
(c) Is the image real or virtual?
(d) Magnifying glasses are used in the eyepieces of refracting telescopes.
One such telescope used to observe stars is shown below.
light from
star
eyepiece
Y
X
(i) What names are given to the telescope parts labelled X and Y on the
diagram?
(ii) Explain why part Y should have a large diameter.
(iii) What is the purpose of the eyepiece in this telescope?
3.
The Chinese first used rockets in the thirteenth century. These rockets used a type of
gunpowder to fuel them. Most modern rockets are liquid fuelled but work on the same
principle as the early rockets.
(a) Explain using Newton’s third law how a rocket engine propels a rocket forward.
(b) A multistage rocket of mass 1·6 x 105 kg is preparing for lift off from Earth. The
rocket engines provide a constant thrust of 2·2 x 106 N.
U
S
A
Calculate the initial acceleration of the rocket.
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(c) The acceleration of the rocket increases as it burns up fuel even though the thrust
provided by the engine remains constant. Explain why.
(d) Once in space the rocket engines are switched off. Describe the motion of the
rocket now and explain its motion in terms of Newton’s laws.
The graph below shows how the speed of a different rocket varied with time after lift
off.
(e) Calculate the initial acceleration of the rocket.
(f) How far did the rocket travel in the 500 seconds shown?
4.
In the future travel to other planets may be possible.
During a ‘virtual reality’ flight, Spacekid observes the following :
A
Walking on the moon seemed effortless but on Jupiter his boots felt as though
they were being held down.
B
Take off from Earth needed less engine thrust than take off from Neptune.
C
Rocket motors could be switched off during interplanetary flight.
D
When a 1·2 kg hammer was dropped on Saturn its time and vertical velocity were
recorded as:
Time (s)
0·5
1·0
1·5
2·0
2·5
Velocity (m/s)
5·5
11
16·5
22
27·5
(a) Explain observation A.
(b) Draw a diagram showing the forces acting on a rocket during take off.
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Use the values of “g” from the data sheet on page 24 to explain, in terms of
the forces acting on the rocket, why take off requires more engine thrust on
Neptune.
(c) If the rocket has a mass of 3 x 107 kg and the engine thrust is 3·9 x 108N,
calculate the acceleration of the rocket at take off from Earth.
(d) Explain observation C
(e) Use the results from D to plot a speed time graph of the hammer falling on
Saturn.
(f) From the graph:
(i) How far did the hammer fall?
(ii) Calculate the gravitational field strength on Saturn.
(g) Spacekid has a mass of 40 kg. On which planet, Earth or Saturn, is he heavier?
Justify your answer.
5.
A space shuttle of mass 2 x 106 kg was travelling with a speed of 9 000 m/s as it
entered the Earth’s atmosphere. The speed of the shuttle dropped to 100 m/s at touch
down, at which point the brakes were applied, bringing the shuttle to rest.
(a) Explain why the speed of the shuttle decreased from 9 000 m/s to 100 m/s before
the brakes were applied.
(b) How much kinetic energy did the shuttle lose before the brakes were applied?
(c) How much heat energy was created as the shuttle speed dropped from 9000 m/s
to 100 m/s?
(d) The shuttle was covered with special heat-resistant tiles. Why was this necessary?
(e) The specific heat capacity of the heat-resistant material used in the tiles is
35 700 J/kg0C.
The temperature of the tiles should increase by no more than 1 300 0C during
re-entry. What mass of tiles would be required to absorb all of the heat energy
produced?
(f) Explain why in practice the mass of the tiles was less than calculated in part (e).
(g) How much work was done by the brakes to bring the shuttle to rest?
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22
The Ultimate Collection of Physics Problems - Space Physics
6.
Use the information on the data sheet to answer the following:
(a) On which planet would a 3 kg rock fall fastest. Explain your answer.
(b) On which planets would the same rock fall most slowly. Explain your answer.
A rock is projected on Saturn as shown .
20 m/s
(c) Use your knowledge of how the gravitational field strength affects falling objects
to copy and complete the following table of vertical velocity and time for the
rock falling on Saturn..
Time (s)
Vertical velocity (m/s)
0
0
1
2
3
4
5
(d) Draw a speed time graph for both the horizontal and vertical motion of the rock
within five seconds of being thrown.
(e) Use the graphs to calculate both the horizontal and vertical distance travelled by
the rock in the first three seconds.
(f) How long will the rock take to reach a vertical speed of 132 m/s.
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The Ultimate Collection of Physics Problems - Space Physics
Appendix (i)
Data Sheet
Speed of light in materials
Material
Speed in m/s
Air
3 x 108
Carbon dioxide
3 x 108
Diamond
12 x 108
Glass
20 x 108
Glycerol
2.1 x 108
Water
23 x 108
Gravitational field strengths
Gravitational field strength
on the surface in N/kg
Earth
10
Jupiter
26
Mars
4
Mercury
4
Moon
16
Neptune
12
Saturn
11
Sun
270
Venus
9
Uranus
117
Pluto
42
Specific latent heat of fusion of materials
Material
Specific latent heat of
fusion in J/kg
Alcohol
099 x 105
Aluminium
395 x 105
Carbon dioxide
180 x 105
Copper
205 x 105
Glycerol
181 x 105
Lead
025 x 105
Water
334 x 105
Specific latent heat of vaporisation
of materials
|Material
Sp.l.ht vap(J/kg)
Alcohol
112 x 105
Carbon dioxide
377 x 105
Glycerol
830 x 105
Turpentine
290 x 105
Water
226 x 105
Speed of sound in materials
Material
Speed in m/s
Aluminium
5 200
Air
340
Bone
4 100
Carbon dioxide
270
Glycerol
1 900
Muscle
1 600
Steel
5 200
Tissue
1 500
Water
1 500
Specific heat capacity of materials
Material
Specific heat
capacity in J/kgoC
Alcohol
2 350
Aluminium
902
Copper
386
Glass
500
Glycerol
2 400
Ice
2 100
Lead
128
Silica
1 033
Water
4 180
Steel
500
Melting and boiling points of materials
Material
Melting
Boiling
point in oC point in oC
Alcohol
-98
65
Aluminium
660
2470
Copper
1 077
2 567
Glycerol
18
290
Lead
328
1 737
Turpentine
-10
156
SI Prefixes and Multiplication Factors
Prefix
Symbol
Factor
giga
mega
kilo
milli
micro
nano
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G
M
k
m

n
1 000 000 000=109
1 000 000
=106
1 000
=103
0001
=10-3
0000 001
=10-6
0000 000 001=10-9
24
The Ultimate Collection of Physics Problems - Space Physics
Appendix (ii) Answers to Numerical Problems
(b) 1.5 m/s2
(c) no; thrust is less
than weight
(d) 5 m/s2
(e) 6 m/s2
(f) 5.58 x 107 N
Section 1
Signals from Space
5.(c) Saturn & Venus
(d) Neptune
Distances in Space(p2)
1. 9.46 x 1015 m
2. 2.55 x 1017 m
3. 40 light years
4. 300 years
5. 19 210 s
6. 9.46 x 1017 km
7. 4.2 light years
8. 7 x 1013 s
( 2.2 million years)
9. 1.49 x 108 km
10. 9 570 s
Ray Diagrams (p3)
1.(a) 6cm
(b) inverted
(c) real
2.(a) image height= 3cm
image distance=6cm
3.(a) real, diminished
inverted
(b)real,samesize, inverted
(c) virtual, magnified,
upright
4.(a) 8 mm
(b) 4 mm
(c) 10 mm
5.(a) 5 cm
(b) 12 cm
6. 2 kg stone on
Neptune
7. 546 N
8. 60 N
9. 0.44 kg
10. Jupiter
Weight,Thrust&
Acceleration(p7)
1.(a) 1.4 x 106 N
(b) 40 500 N
(c) 20 000 kg
(d) 3.6 x 108 kg
(e) 0.125 m/s2
(f) 1.33 m/s2
2. 0.75 m/s2
3. 4.2 x 106 N
4. 2 x 106 kg
5. 1.33 m/s2
6.(a) 30 ; 10
(b)19 000 ; 9.5
(c)15 000 ; 5 000 ;
3.33
(d) 500 000;
50 000; 1
(e)700 000;
140 000; 2
(f) 760 000;
136 800; 1.8
7.(a) 8 N
Section 2
Space Travel
Weight (p5)
1.(a) 120 N
(b) 1 116 N
(c) 10 N/kg
(d) 10 N/kg
(e) 58.33kg
(b) 5 m/s2
(c) 13.4 m/s2
8.(a) 4 x 106 N
(b) 1.6 x 107 N
(c) 2 x 107 N
(d) 6.56 x 106 N
9.(a) 16.67 m/s2
(b) 2.6 m/s2
(b) 24 m/s
(c) 28.8 m
Re-Entry(p15)
(f) 5.8 kg
2. 700 N
3. 2.88 kg
5.(a) Jupiter
(b) Mars & Mercury
(c) 0 m/s2
(d) 10 m/s2
(e) 11.5 m/s2
(f) 8 m/s2
10.(a) 1.8 x 106 kg
(b) 13 333 oC
5.(a) 8.75 x 108 J
(b) 39 062.5 oC
6.(a) 1.25 x 1010 J
(b) 1.25 x 1010 J
Projectiles (p11)
1.(a) 40 m
(b) 20 m/s
(c) 20 m
2.(a) 1 200 m
(b) 120 m/s
(c) 720 m
3.(a) 300 m
(b) 100 m/s
4.(a) 8 x 107 m
(b) 2 000 m/s
(c) 20 000 m
5.(a) 0.5 s
(b) 5 m/s
(c) 1.25 m
6.(a) 0 m/s
(b) 100 m/s
7.(a) 0 m/s
(b) 12.5 s
8. h. dist. = 1 200 m
v. dist = 1 350 m
9.(a) 200 m
(b) 0.75 m/s2
(c) 150 m
10.(a) 84 m
1. 1.6 x 107 J
2. 8.1 x 109
3.(a) 6.4 x 1013J
(b) 6.4 x 1013J
4.(a) 2.4 x 108J
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6.(c) 35 714 J/kgoC
7 (a) 4.8 x 1010 J
(b) 4.8 x 1010 J
(c) 13 333 oC
8.(a) 61 660.5 J
(b) 61 660.5 J
9.(a) 1.2 x 1014 J
(b) 1.2 x 1014 J
(c)3 x 106 N
10.(a) 8.1 x 109 J
(b) 8.1 x 109 J
(c) 2 025 m
Revision Questions
Credit Level(p19)
1.(c) 2.08 x 1019 km
2.(b)5 cm
3.(b) 3.75 m/s2
(e) 8.5 m/s2
(f) 1.02 x 106 m
4.(c) 3 m/s2
(e) (i) 34.38 m
(ii) 11 N/kg
(f) Saturn
5.(b) 8.1 x 1013 J
(c) 8.1 x 1013 J
(e) 1.75 x 106 kg
(g) 1 x1010 J
6.(a) Jupiter
(b) Mars & Mercury
(c) velocities (m/s):
(0), 11, 22,
33,44,55.
(e) h.dist.: 60 m
v. dist.: 49.5 m
(f) 12 s
25