3C20m - Tekanan permukaan, memilih jengkaut yang terbaik

11	Diagram below shows a container which is full of liquid Y. Its base area is A m2 and its height is h m. The density of the liquid Y is p kgm-3.
	Rajah di bawah menunjukkan satu bekas diisi penuh dengan cecair Y. Luas tapak bekas itu adalah A m2 dan tingginya h m. Ketumpatan cecair Y diberi sebagai p kgm-3.
	(a)	What is meant by pressure?
		Apakah yang dimaksudkan dengan tekanan?
		[ 1 mark/ markah]
	(b)	Write a formula for each of the following quantities.
		Tuliskan formula untuk setiap kuantiti berikut.
		(i)	Volume of the liquid Y
			Isipadu cecair Y
			[ 1 mark/ markah]
		(ii)	Mass of liquid Y
			Jisim cecair Y
			[ 1 mark/ markah]
		(iii)	Force which acts on the base of the container
			Daya yang bertindak pada dasar bekas air itu.
			[ 1 mark/ markah]
	(c)	By using the formulae in (b), derive the SI unit for pressure
		Dengan menggunakan formula daripada (b), terbitkan unit SI untuk tekanan.
		[ 3 mark/ markah]
	(d)	A small submarine can withstand a maximum water pressure of 3.0 × 105 Nm-2. Find the greatest depth that can be descended by the submarine. (Density of water = 1.0 × 103 kgm-3)
		Sebuah kapal selam kecil dapat menampung tekanan air maksima 3.0 × 105 Nm-2. Tentukan kedalaman air maksima yang dapat dimasuki oleh kapal selam itu. (Ketumpatan air = 1.0 × 103 kgm-3)
		[ 3 mark/ markah]
	(e)	You are asked to investigate the characteristics of each backhoes in table and choose a backhoe that can do heavy works, an example of a backhoe is shown in diagram. Explain the suitability of the characteristics each backhoes. Determine the most suitable backhoe. Give reason for your choice.
		Anda ditugaskan untuk mengkaji ciri-ciri setiap jengkaut dalam jadual dan pilih sebuah jengkaut yang boleh melakukan kerja berat. Contoh jengkaut diberikan dalam Rajah. Terangkan kesesuaian ciri-ciri setiap jengkaut. Pilih jengkaut yang paling sesuai. Berikan sebab kepada pilihan anda.
		Type of Backhoe Jenis jengkaut		Characteristics of Backhoe
				Size of tyre Saiz tayar	Fluid used in hydraulic system Bendalir yang digunakan dalam sistem hidraulik	Mass Jisim	Base area Luas tapak	Centre of gravity Pusat graviti
		M		Large Besar	Liquid Cecair	Large Besar	Large Besar	Low Rendah
		N		Large Besar	Liquid Cecair	Small Kecil	Large Besar	Low Rendah
		P		Large Besar	Gas Gas	Large Besar	Small Kecil	High Tinggi
		Q		Medium Sederhana	Liquid Cecair	Large Besar	Medium Sederhana	Low Rendah
		R		Large Besar	Liquid Cecair	Large Besar	Medium Sederhana	High Tinggi
		[ 10 marks/ markah]
		JAWAPAN 6 (a) Perpendicular force per unit area acting on a surface // force per unit area 1 (b) (i) A × h 1 (ii) ƥ × A × h // ƥAh // ƥV 1 (iii) ƥhAg // ƥVg 1 (c) P = ƥhAg // P = ƥhg A Unit : kgm-3 × m2 × ms-2 kgm-1s-2 1 1 1 (d) 3.0 × 105 1 × 103 × 10 30 m (with unit) 1 2 (e) Size of the type is large Prevent backhoe from sinking into soft ground Fluids used in hydraulic system is liquid Not easy compress compared to the gases // high power Large mass Avoid backhoe from moving Large base area Ensure that the backhoe will not collide Centre of gravity is low More stable The most suitable backhoe is M. Large tyre, fluids use in hydraulic system is liquid, large mass, large base area and the centre of gravity is low. 1 1 1 1 1 1 1 1 1 1 1 1 20