Answer for The Bengkel 2018

NO. SOALAN			JAWAPAN	MARKAH
9	(a)	(i)	Define pressure. Force per unit area	1
		(ii)	State the observation and analysis correctly ·       Plastic bottle in Diagram 9.1 inflates // Plastic bottle in Diagram 9.2 crumple ·       Diagram 9.1 higher altitude // Diagram 9.2 lower altitude ·       Volume of the gas in Diagram 9.1 is greater // Volume of the gas in Diagram 9.2 is less ·       Atmospheric pressure in Diagram 9.1 is  less // Atmospheric  pressure in Diagram 9.2 is greater ·       The pressure of the gas in the bottle in Diagram 9.1is equal to the pressure of the gas in the bottle in Diagram 9.2. State the conclusion correctly ·       The greater the atmospheric pressure, the lesser the volume of the gas ·       The higher the altitude, the lower the atmospheric pressure	1 1 1 1 1 1 1 Max: 5
	(b)		State the explanation why aerosol must be kept away from fire correctly ·       The aerosol can explodes ·       The greater the temperature, the greater the kinetic energy molecules of gas ·       Greater frequency of collision between the molecules and the wall of the container. ·       The greater impulsive force ·       The greater gas pressure ·       F α P	1 1 1 1 1 1 Max: 4
	(c)		State the suggestions and explanations correctly The body of hand air pump made of stronger material. Withstand high pressure // Not break easily The size of cylindrical body is large // Large diameter Pump up larger volume of air. Install Bourdon Gauge Measure the pressure of air correctly Body made of high specific heat capacity of material. Not easy heat up // Hot slower Stronger piston Not easily break Body made of low density of material. Lighter // Light // Portable // Smaller mass Tight connection between hose valve and tire vale Prevent leakage of air pressure Flexible hose Bend easily Longer handle Easier to hold Hand air pump powered by motor More efficient // Pump air faster	1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Max: 10
			FULL MARKS	20

NO. SOALAN			JAWAPAN	MARKAH
10	(a)		State the meaning of coherent sources. Sources of waves which produce waves that vibrates with same frequency and same phase / constant difference phase.	1
	(b)	(i)	Distance between two loud speakers in Diagram 10.1 < Diagram 10.2 // vice-versa. Distance between two consecutive loud sounds in Diagram 10.2 < Diagram 10.1 // vice-versa. Frequency of sound wave in Diagram 10.1 and Diagram 10.2 are equal. The higher the distance between two loud speakers, the lower the distance between two consecutive loud sounds.	1 1 1 1
		(ii)	Name the phenomenon involved. Inteference.	1
	(c)		Explain student P, Q and R can hear the sound. Diffraction of waveoccured // The waves spread around the corner. Explain why student P can not hear the sound clearly compare to the student R. The amplitude of sound wave hear by student R is greater, More sound energy received. Suggest one way so that student P can hear the sound clearly. Increase the volume // High amplitude of sound wave	1 1 1 1
	(d)		Aspects Explanation Ultrasonic waves // very  high frequency of sound wave high frequency // high energy wave High frequency High energy // able to penetrate the deep sea // able to travel further Short wavelength Less diffracted // Travel in narrow beam  // less energy loss Phenomenon  Reflection of wave To produce echo // reflected of ultrasonic waves Transmitter / receiver // Transducer To transmit wave / to receive wave	1,1 1,1 1,1 1,1 1,1
			FULL MARKS	20

NO. SOALAN			JAWAPAN	MARKAH
11	(a)		Name the physics principle involved. Archimedes’ Principle	1
	(b)		Explain why the ship can float in sea water. Balance force Buoyant force = weight of the ship.	1 1
	(c)	(i)	State the purpose of plimsoll lines. To ensure the ship will not be overload.	1
		(ii)	State why plimsoll lines have many levels. Different water zone has different density of water.	1
	(d)		Explain the suitable characteristics. Modification Explanation Streamlined shape To reduce water resistance High total mass of ship To increase the stability of the ship High width of ship base Increase the vloume of the water displaced High volumes of air space in the ship Greater buoyant force StructureW (describe all characteristics)	1,1 1,1 1,1 1,1 1,1
	(e)	(i)	Calculate the volume of water displaced. V of water displaced by the load and the wooden block = V wooden block V wooden block = 2.5 kg / 550 kg m-3                          = 0.00455 kg	1 1
		(ii)	Calculate the mass of the load X. W load + W wooden block = W water displace W load = (1000 kg m-3 x 0.00455 kg x 10 m s-2) – (2.5 kg x 10 m s-2)             = 20.5 N Mass load = 2.05 kg	1 1 1
			FULL MARKS	20

NO. SOALAN			JAWAPAN	MARKAH
12	(a)		State the meaning of electromagnetic induction. The produce of induced current when a wire cutting a magnetic flux.	1
	(b)		Explain briefly the working principle of a direct current generator. External force is applied Operating based on electromagnetic induction. When the coil horizontal, the wire cut the magnetic flux. Current is produced. Use Faraday Law Use commutator	1 1 1 1 1 1 Max: 4
	(c)		Explain the suitablity for construction of direct current generator. Criteria Explanation High number of turns Increase the speed Coil mounted on laminated soft iron core Concentrates the magnetic flux on the coil Use commutator Produce direct current output Curve-shaped magnet Produce radial magnetic field Generator R (describe all criteria)	1,1 1,1 1,1 1,1 1,1 1,1
	(d)	(i)	Name the type of transformer used. Step-up transformer
		(ii)	Calculate the current flow in the bulb. I = 0.25A	1 1
		(iii)	Calculate the number of secondary coil. N = 800 turns	1 1
			FULL MARKS	20