Supp[1]. Ex. - 09 Space travel.doc

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

Oxford University Press - 135 -


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D



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*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


BC

D

A


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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


to water to water

C D

to water to water

X

10 NY


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**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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*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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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


5 N


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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


movement of the tail

AB

C

D


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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


3. Long March 2F rocket 4. Space shuttle Columbia


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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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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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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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reaction, opposite



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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


blade


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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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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


rocket

lunar landingvehicle


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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.


wall


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*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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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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*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?

_____________________________________________________________

_____________________________________________________________


trigger

water


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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.


force on

rocket

force onwater


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*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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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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*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

_____________________________________________________________

__________________________________________________________________________________________________________________________


Diagram 1 Diagram 2

atmosphere ofplanet Y

path A

path B

Planet Y

spacecraft


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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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Supp[1]. Ex. - 09 Space travel.doc