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7/29/2019 Supp[1]. Ex. - 09 Space travel.doc
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Living Science (Second Edition) Supplementary Exercise Unit 9
Unit 9 Space Travel
A Multiple-choice questions
1 Which of the following instruments can be used to measure force?
A B
C D
A
2 Which of the following correctly shows all forces acting on a block when it falls
from a height in air?
A No forces acts on the block.
B
C
D
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Living Science (Second Edition) Supplementary Exercise Unit 9
D
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Living Science (Second Edition) Supplementary Exercise Unit 9
*3 A ball is thrown upwards and it falls back onto the ground. What is the reason
that the ball falls back?
A The air resistance stops the ball from going up, so it drops.
B The ball loses all its energy so it drops.
C The force of gravity pulls the ball downwards.
D The weight of the ball is large.
C
**E4 If a planet has a shape as shown in the following diagram, at which position is
the weight of a person the greatest?
B
E5 Which of the followings are correct about radiation?
(1) It can be harmful to our health.
(2) It carries energy.
(3) It can travel in vacuum.
A (1) and (2) only
B (1) and (3) only
C (2) and (3) only
D (1), (2) and (3)
D
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BC
D
A
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Living Science (Second Edition) Supplementary Exercise Unit 9
6 What is the magnitude of the frictional force acting on block X if the set-up is
stationary?
A 0 NB 5 N
C 10 N
D 20 N
C
7 Which of the following objects would sink at the fastest rate if they were dropped
into a bucket of water? All objects have the same weight.
A B
A
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to water to water
C D
to water to water
X
10 NY
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Living Science (Second Edition) Supplementary Exercise Unit 9
**8 What are the forces acting on the spacecraft with opened parachutes when it
travels back from space to the Earth through the atmosphere? (The arrows
represent the forces.)
A B
C D
A
9 What is the change in energy when a spacecraft travels from space back to the
Earth through the atmosphere?
A Potential energy
heat energy + light energyB Potential energy heat energy + light energy + kinetic energy
C Kinetic energy heat energy + light energy + potential energy
D Heat energy kinetic energy + potential energy
B
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Living Science (Second Edition) Supplementary Exercise Unit 9
*E10 Which of the following statements about mass and weight is correct?
A Both mass and weight are forces.
B Both mass and weight have the unit of kilogram.
C The weight of an object can be different at different places.
D The mass of an object can be different at different places.
C
E11 Which of the following design of spacesuit protect an astronaut by conduction?
A Tinted visor ()
B Shiny spacesuit surface
C Water-cooled underwear
D Toughened overshoe
C
12 Which nations have sent human to space?
A China, USSR and USA
B USA, Germany and France
C USSR, USA and Japan
D The UK, Germany and Australia
A
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Living Science (Second Edition) Supplementary Exercise Unit 9
13 As shown in the following diagram, Jenny places a block on a table and pulls it
with 5 N towards the right. What is the reaction acting on Jenny?
A 0
B 5 N (to the left)
C 5 N (to the right)
D 10 N (to the left)
B
14 What are the forces acting on the rocket as shown in the following diagram?
(1) Propulsive force moving the rocket upwards.
(2) Gravitational force pulling the rocket downwards.
(3) Air resistance opposing the motion of the rocket.
A (1) and (2) only
B (1) and (3) only
C (2) and (3) only
D (1), (2) and (3)
D
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5 N
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Living Science (Second Edition) Supplementary Exercise Unit 9
15 What is the unit of measurement of the following instrument?
A m
B N
C C
D g
D
16 The following diagram shows how a fish pushes water with its tail to swim
forward as seen from above. Which of the following shows the direction of the
reaction acting on the tail of the fish?
B
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movement of the tail
AB
C
D
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Living Science (Second Edition) Supplementary Exercise Unit 9
17 Which country has sent human to land on the Moon?
A USSR
B China
C USA
D Japan
C
18 Arrange the following rockets in the correct order of development.
1. Saturn V rocket 2. V2 missile
A 2, 1, 4, 3
B 2, 1, 3, 4
C 3, 1, 4, 2
D 4, 3, 2, 1
A
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3. Long March 2F rocket 4. Space shuttle Columbia
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Living Science (Second Edition) Supplementary Exercise Unit 9
E19 Which of the following is not a spin-off of space technology?
A Satellite communication
B Pencil
C Non-scratch glasses
D Small lasers in CD driver
B
20 Who was the first human sent to the space?
A Yang Li-wei
B Gargarin
C Neil Armstrong
D Michael Collins
B
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Living Science (Second Edition) Supplementary Exercise Unit 9
B True or false questions
1 Human has already landed on Mars.
F
2 The first Chinese manned spacecraft is Shenzhou 5.
T
3 Magnetic force holds the Moon in orbit around the Earth.
F
E4 When measured on the Moon and on the Earth, the weight of an object is the
same but the mass of it is different..
F
5 Our masses decreases as we are falling down.
F
6 Rockets need to carry oxygen for burning fuels.
T
E7 Heat can be transferred from the cold part to the hot part along an object by
conduction.
F
8 The first satellite was launched by USSR.
T
9 Friction always opposes the motion of an object.
T
10 Rocket was invented by the German.
F
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Living Science (Second Edition) Supplementary Exercise Unit 9
C Fill-in-the-blanks
1 A ____________________ is used to measure force. The unit of force is
________________.newton balance / spring balance, newton (N)
2 A force can change the ________________ of a moving object.
speed / direction
3 Electrostatic force and magnetic force are examples of ________________
forces.
non-contact
4 A spacecraft continues to move in space without firing its engine because in the
space there is no __________________ to slow down its motion.
air friction / air resistance
5 USA has developed __________________ which are reusable and can travel
between the Earth and the space stations.
space shuttles
E6 Astronauts wear ________________ for protection when they work outside the
aircraft.
spacesuits
7 The shape of an aeroplane is ________________ in order to reduce air friction
during flight.
streamlined, air friction
8 There is no air in the space between the Earth and the Sun, i.e. it is a
________________.
vacuum
9 Energy can be transferred across a vacuum by ________________.
radiation
10 Action and ________________ are equal and ________________.
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Living Science (Second Edition) Supplementary Exercise Unit 9
reaction, opposite
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Living Science (Second Edition) Supplementary Exercise Unit 9
D Short questions
1 When we skate on ice, there is a thin layer of water between the ice surface and
the blades of the skates. From the information given, explain briefly why we canskate at a high speed on ice surface.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Answer:
The layer of water between the blade and the ice surface greatly reduces the friction
acting on the blade. Hence, we can skate at a high speed on ice surface.
2 Is a seahorse designed to be a good swimmer? Give a reason for your answer.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Answer:
Seahorse is not designed to be a good swimmer. It is because it does not have
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blade
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Living Science (Second Edition) Supplementary Exercise Unit 9
streamlined body.
3 List any two design features of a space shuttle that protect astronauts inside when
they re-enter the Earth from the space.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Answer:
The surface of a space shuttle is covered with insulating tiles that protect the space
shuttle from burning.
Parachutes are used to slow down the space shuttle so that the space shuttle can land
more safely.
(Or other reasonable answers.)
*4 Michael wants to open a window. He finds that he needs to push it hard before he
can open it. Suggest a reason why Michael has to apply a large force to open the
window and how he can improve the situation.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Answer:
Michael has to push the window hard before he can open it because the friction
between the moving parts of the hinges of the window is large.
He should apply some lubricating oil at the hinges to reduce the friction.
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Living Science (Second Edition) Supplementary Exercise Unit 9
5 A block is pushed on a plane as shown in the following diagram.
a If the block moves towards the left, what is the direction of the friction
acting on the block? Indicate the friction on the diagram by an arrow.
b Is there any friction acting on the block if it rests on an inclined plane?
_________________________________________________________________
_________________________________________________________________
Answer:
a
b There is friction acting on the block if it rests on an inclined plane. Friction
prevents the block from sliding down.
6 Why does a rocket need a streamlined shape while a lunar landing vehicle does
not?
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Answer:
Since the rocket has to fly in air, its body should be streamlined to reduce air
resistance when it moves in air. However, since the lunar landing vehicle travels only
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rocket
lunar landingvehicle
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Living Science (Second Edition) Supplementary Exercise Unit 9
in space (a vacuum), it does not need a streamlined shape.
7 Paul sits on a cart and pushes against a wall. By considering the force acting on
the wall by Paul, determine the direction of force acting on Paul by the wall and
the motion of Paul after the push.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Answer:
The force acting on the wall by Paul points towards the left. Hence, the reaction
acting on Paul by the wall points towards the right and Paul will move towards theright after the push.
*E8 How does a spacesuit protect an astronaut when he faces the Sun in space? State
two design features of the spacesuit.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Answer:
When an astronaut faces the Sun in space, the tinted visor reflects radiation and
prevents excessive radiation from reaching the astronaut. Also the shiny surface of the
spacesuit reflects radiation and reduces the absorption of radiation from the Sun.
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wall
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Living Science (Second Edition) Supplementary Exercise Unit 9
*E9 John said that he can lift up a block of 100 kg on the Moon but not on the Earth.
What is his reason?
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Answer:
Since the weight of an object on the Moon is only one-sixth of that on the Earth.
Therefore, the weight of the block of 100 kg is much lighter on the Moon than that on
the Earth and John can lift it on the Moon.
*10 If the fan cart in the following diagram is placed on the Moon, can it move when
the fan is turned on?
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
Answer:
Since there is no air on the Moon, even if the fan of the cart is turned on, no force
(reaction) will act on the cart and the cart will not move.
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Living Science (Second Edition) Supplementary Exercise Unit 9
E Long questions
**1 Tommy sits on a cart and throws sandbags of different weight.
a Explain why the cart moves as Tommy throws a sandbag.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
b In two trials, Tommy throws sandbags with 1 kg and 5 kg at the same speed.
In which trial does Tommy move at a higher speed? Why?
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
c The cart can only move for a short while. Explain briefly.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
Answer:
a When Tommy throws a sandbag, a reaction acts on Tommy by the sandbag and
hence he, together with the cart, moves.
b Tommy moves at a higher speed when he throws the sandbag with 5 kg. It is
because he applies a larger force in throwing a heavier sandbag and a larger
reaction force acts on him. Hence he can move faster.
c It is because friction acts on the cart when it moves. Therefore, the cart slows
down and stops.
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Living Science (Second Edition) Supplementary Exercise Unit 9
*2 The following diagram shows a water rocket. Before the launch of the rocket, air
is pumped into the rocket. And when the rocket is launched, it flies upwards
while water is ejected downwards.
a Draw the forces acting on the water ejected and on the rocket when the
rocket is launched.
b What are the terms given to the forces in (a)? Do the forces have the same
sizes?
_____________________________________________________________
_____________________________________________________________
c Suggest a method to increase the launching speed of the rocket.
_____________________________________________________________
_____________________________________________________________
d When the rocket is launched, what energy of the rocket increases?
_____________________________________________________________
_____________________________________________________________
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trigger
water
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Living Science (Second Edition) Supplementary Exercise Unit 9
Answer:
a
b They are called action and reaction. They have the same size.
c Pump more air into the rocket.
(or other reasonable answers)
d The kinetic energy and potential energy of the rocket increases.
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force on
rocket
force onwater
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Living Science (Second Edition) Supplementary Exercise Unit 9
*3 The following diagrams show a space shuttle and a spacecraft when they re-enter
the Earth through the atmosphere.
a Write down the forces that act on them when they re-enter the Earth. Which
force attracts them towards the Earth and which force opposes their motion?
_____________________________________________________________
_____________________________________________________________
b Does the space shuttle or the spacecraft move faster across the atmosphere?
Why?
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
c In order to avoid being burnt out, what has been installed to the spaceshuttle?
_____________________________________________________________
Answer:
a Force of gravity attracts them towards the Earth.
Air resistance oppose their motion.
b The spacecraft moves faster because its bottom has a smaller surface area than
that of the space shuttle, the air resistance is also less than that of the space
shuttle.
c The surface of the space shuttle is covered with insulating tiles.
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Living Science (Second Edition) Supplementary Exercise Unit 9
E4 Armstrong together with Collins and Aldrin were sent to the Space and they
successfully finished the mission of landing on the Moon in 1969.
a When astronauts travel to the space, they would feel weightlessness.
Describe this phenomenon briefly.
_____________________________________________________________
b When Armstrong landed on the Moon, he felt himself much lighter than
when he was on the Earth. Why?
_____________________________________________________________
_____________________________________________________________
c Owing to the weightlessness, the life of astronauts in space is different from
that on the Earth. Give an example of the change in life style of astronauts
in space.
_____________________________________________________________
_____________________________________________________________
_____________________________________________________________
d The technology used in space exploration has been used in our daily life.
Give an example of such technology.
_____________________________________________________________
_____________________________________________________________
Answer:
a Weightlessness is the situation in which we cannot feel our weight.
b It is because the gravity of the Moon is only one-sixth of that of the Earth.
Hence, Armstrong felt much lighter on the Moon than on the Earth.
c In space,
astronauts have to use specially designed toilet,
astronauts have to themselves in beds, or
astronauts have to add water through a long needle inserted into the sealed
containers with foods in dried form.(any ONE or other reasonable answers)
d Small lasers in CD driver
Scratch-resistant lenses
Dried food and high energy food
(any ONE or other reasonable answers)
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Living Science (Second Edition) Supplementary Exercise Unit 9
*E5 A spacecraft travels to planet Y and is going to land on it. Planet Y has
atmosphere and gravity similar to that of the Earth. As the spacecraft approaches
planet Y, it may take path A or path B to travel through the atmosphere as shown
in diagram 1. When it nearly reaches the ground, its parachutes are opened and
its rocket engine is fired as shown in diagram 2.
a List two problems that the spacecraft encounters when it passes through the
atmosphere of planet Y
_____________________________________________________________
__________________________________________________________________________________________________________________________
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Diagram 1 Diagram 2
atmosphere ofplanet Y
path A
path B
Planet Y
spacecraft
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Living Science (Second Edition) Supplementary Exercise Unit 9
b Draw and label the forces acting on the landing spacecraft in the following
diagram.
c The oxygen content of the atmosphere of planet Y is only 10% of that of the
Earth. How can astronauts survive outside the spacecraft?_____________________________________________________________
_____________________________________________________________
d The force of gravity of planet Y is 3/4 of that of the Earth. If an astronaut
weighs 800 N on Earth, what is his weight on planet Y?
_____________________________________________________________
_____________________________________________________________
Answer:a The speed of the spacecraft is very high. And the temperature of the spacecraft is
very high.
b
c Astronauts should put on spacesuits with oxygen tank.
d The weight of the astronaut on Planet Y = 800 N 3 /4 = 600 N
force of gravity
air resistance
uplifting force ofrocket engine
air resistance
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