(a) (i) State Archimedes’ principle.
Nyatakan prinsip Archimedes.
[1 mark]
(ii) Explain why a balloon filled with helium
gas rises up in the air.
Jelaskan mengapa sebuah belon yang diisi dengan gas
helium naik ke udara.
[4 marks]
(b) Diagram 11.1 shows four hot air balloons,
P, Q, R and S with different features. You are required to determine the most
suitable hot air balloon which is able to
carry three or four people to a higher altitude in a shorter time.
Study
the features of all the four hot air balloons from the following aspects:
-
The size of the
balloon
-
The number of the
burners
-
The type of the
fabric of the balloon
-
The temperature
of the air in the balloon
Explain
the suitability of the aspects.
Justify your choice.
Rajah 11.1 menunjukkan empat
belon udara panas, P, Q, R dan S dengan ciri-ciri yang berlainan. Anda
dikehendaki menentukan belon udara panas yang paling sesuai untuk membawa tiga
atau empat orang ke altitud yang lebih tinggi dalam masa yang lebih pendek.
Kaji ciri-ciri bagi kesemua
empat belon udara panas itu dari aspek berikut:
- Saiz belon
- Bilangan pembakar
- Jenis fabrik bagi belon
- Suhu udara di dalam belon
Jelaskan
kesesuaian aspek-aspek itu.
Beri sebab bagi pilihan anda.
(c) Diagram
11.3 shows a cylindrical glass tube of uniform cross sectional area of 2 cm2.
The glass tube contains lead shots and floats upright in water.
Rajah 11.3
menunjukkan sebatang tiub kaca dengan luas keratan rentas seragam 2 cm2.
Tiub kaca itu mengandungi butir-butir plumbum dan sedang terapung tegak di
dalam air.
The density of water is 1 g cm–3,
Ketumpatan air ialah 1 g cm–3,
(i) calculate the total mass
of the glass tube and the lead shots.
hitungkan
jumlah jisim tiub kaca dan butir-butir plumbum.
(ii) the tube is then placed
in another liquid of different density.
Determine the minimum density
of liquid for the tube to float in it.
tiub itu kemudian
diletakkan di dalam cecair dengan ketumpatan yang berlainan.
Tentukan ketumpatan
minimum cecair yang membolehkan tiub itu terapung di dalamnya.
[5 marks]
State the meaning correctly
|
- Archimedes’
principle states that the buoyant force on an object immersed in a fluid is
equal to the weight of fluid displaced by the object.
|
Explain why a balloon filled
with helium gas rises up in the air correctly
|
- The balloon acted by two forces: Upthrust
and the weight of the balloon
|
- The density of helium gas is less than the density of surrounding
air
|
- Upthrust equals to the weight of the air displaced by the
ballloon
|
- Upthrust is higher than the weight of the balloon
|
M1 States a suitable size of
the balloon
|
- Large balloon
|
M2 State the reason for M1
correctly
|
- To produce bigger buoyant / upthrust // Increase the volume of
the air displaced
|
M3 State a suitable number of the burner
|
- Use 2 burners // Many burners
|
M4 State the reason for M3
correctly
|
- To produce bigger flame // heat up the gas in the balloon faster
|
M5 State a suitable type of fabric of the balloon
|
- Synthetic nylon
|
M6 State the reason for M5
correctly
|
- Light-weight, strong and air-proof material
|
M7 State a suitable
temperature of the air in the balloon
|
- High temperature of the air in the balloon
|
M8 State the reason for M7
correctly
|
- Reduce the density /weight of the air in the balloon
|
M9 Choose the most suitable hot air balloon
|
Hot air balloon Q is chosen
|
M10 State the reason
correctly
|
Large balloon, use 2 burners / many burners, use synthetic nylon and
has high temperature of the air in the balloon // or combination of the
reasons
|
Giving a correct equation
|
Weight = buoyant force = weight of the water displaced
|
W = mg = rwater V g
|
Substitute the equation
correctly
|
m x 10 = (1 × 2 × 12 × 10)
|
Correct answer with unit
|
m = 0.024 kg /24 g
|
Show a correct substitution
|
m = r V
24 = r (14 x 2)
|
Correct answer with unit
|
ρ = 0.83 g cm-3
|