3C20m - Archimedes, belon udara panas, mengira daya apung bot

11 (a) (i) State Archimedes’ principle.
Nyatakan prinsip Archimedes.

[1 mark/markah]

(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/markah]

(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.

[10 marks/markah]

(c) The weight of a boat without load is 12 000 N and the volume of the immersed portion of the boat is 5.0 m3. [ Density of sea water is 1020 kg m-3 ]

Berat sebuah bot tanpa beban ialah 12000 N dan isipadu bahagian tenggelam bagi bot itu ialah 5.0 m3. [ Ketumpatan air ialah 1020 kg m-3 ]

Calculate

Hitungkan

(i) The buoyant force exerted to the boat.

Tujah ke atas yang dikenakan pada bot itu.

(ii) The maximum mass of load that can be supported by the boat so that it will not sink completely.

Jisim maksima beban yang boleh ditampung oleh bot supaya ia tidak tenggelam sepenuhnya.

[5 marks/markah]

Jawapan: 

No		Answer	Marks
11	a (i)	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	1
	(ii)	-  The balloon acted by two forces: Upthrust and the weight of the balloon. - Gas helium dalam belon menyesarkan udara menghasilkan tujah ke atas -  The density of helium gas is less than the density of surrounding air -  Upthrust equals to the weight of the air displaced by the balloon -  Upthrust is higher than the weight of the balloon	1 1 1 1
	b	Characteristic Reason The size of the balloon - Large To produce bigger buoyant / upthrust // Increase the volume of the air displaced The number of the burners - Use 2 burners // Many burners To produce bigger flame // heat up the gas in the balloon faster The type of the fabric of the balloon - Synthetic nylon Light-weight, strong and air-proof material The temperature of the air in the balloon - High Reduce the density /weight of the air in the balloon Q is chosen Because it has 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	2 2 2 2 2
	c (i)	F =  1020 x 5 x 10    =   51 000 N	1 1
	(ii)	12 000 + W  =  51 000 N W =  39 000 N m  =  3 900 kg	1 1 1
TOTAL			20