Answer Key Physical Science

8/12/2019 Answer Key Physical Science

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Answer Key

PHYSICAL SCIENCE (PS)

No. Answer Teachers notes

1a) The greater the height from which the ball is dropped from, the deeper the dent [1].The higher the height, the more gravitational potential energy it has and more energy is beingtransferred when it hits the sand [1]

1b) Objects thrown from high rise buildings have

greater gravitational potential energy than from lowrise buildings which is converted to

greater kinetic energy just before it hits the ground [1/2]

The

transfer of this energy to someone when the object hits will also be greater [1/2] and causegreater injury.

2a It was attracted to the magnet.

b Magnet loses some of its magnetism/ magnetic strength weakens when heated [1/2] SO alonger string is used so the clip can be nearer to the pole of the magnet[1/2] for it to be attracted

c Heating cause a magnet to lose its magnetism/weakens its magnetic strength.

3a) The greater the angle x, the greater is the pulling force. relationship qnanswer

b) The force of 50 units is used to overcome friction between the lower surface of the block andplank.

4a) The paper block some light from reaching the sensorORThe paper is translucent.


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b) No light is able to pass through beyond 6 sheets of paper

c) Use a brighter torchOR

move the torch closer to Xhttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDFRdFBvanAyUlV0YzJfUUxVd2NPWkE&usp=sharing

5a) Matter that is heated do not become lighter or heavier but its mass/weight stays the same.Cup Y moved up because of the expansion of gas/air when heated.

b) Air heated by candle becomes hot. Hot air rises and pushes the cup upwards.

https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdC1tSWRFX1JGaGg5aUxaWFRtcnRIVWc&usp=sharing

6a The only variable that must be changed is the type of materials [1/2] and all other variablesincluding the thickness of material must be kept the same [1/2] .

b Q. The loudness recorded by sensor is the lowest [1/2] SO least sound can reach Ritasbedroom [1/2]

7a - As the mixture of metals move along belt Y, the magnetic metals will be attracted to the magnet inbelt X and the non-magnetic substance will fall into bin D.[1]

- The attraction between the metals and the magnet weakens as the metals move further away fromthe magnet and they will then be collected at bin C.[1]

b ???

8a) light energy ->kinetic energy

b) Faster. More light energy will be converted to more kinetic energy causing the vanes to rotate
https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDFRdFBvanAyUlV0YzJfUUxVd2NPWkE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDFRdFBvanAyUlV0YzJfUUxVd2NPWkE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDFRdFBvanAyUlV0YzJfUUxVd2NPWkE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdC1tSWRFX1JGaGg5aUxaWFRtcnRIVWc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdC1tSWRFX1JGaGg5aUxaWFRtcnRIVWc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdC1tSWRFX1JGaGg5aUxaWFRtcnRIVWc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdC1tSWRFX1JGaGg5aUxaWFRtcnRIVWc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdC1tSWRFX1JGaGg5aUxaWFRtcnRIVWc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDFRdFBvanAyUlV0YzJfUUxVd2NPWkE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDFRdFBvanAyUlV0YzJfUUxVd2NPWkE&usp=sharing


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faster.

c) Energy has been converted to heat (and sound) energy as it overcomes air resistance .

9a) No. The circuit can still be closed if Q is a conductor of electricityb) Yes. Electricity must be able to flow from battery to clip and through Q and then to the other metal

clip to close the circuit.

10a) 5

b) No. Light from the source will never be blocked at all.

c) Place Object X nearer to each other.https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdFRSTGlJRnJSS1Z0LTBxdzRfZlN3cGc&usp=sharing

11a) Light is blocked by opaque objects

b) Walking away.The length of shadow b ecomes longer the more she moves away from the light source (l amp)

If walking away part is notmentioned orwrong, whole qn =0m

c) For the

same duration (time), length of Daisy's shadow changes (decreases) more in period Y thanit changes (increases) in period X

OR- It took a longer time from Daisy's shadow to become shorter than for it to become longer

OR

- The length of the shadow at Y changed faster than the shadow at X.

https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGhnVUFkRVNoRjlmazJSSFA5ejRKR0E&usp=sharing
https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdFRSTGlJRnJSS1Z0LTBxdzRfZlN3cGc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdFRSTGlJRnJSS1Z0LTBxdzRfZlN3cGc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdFRSTGlJRnJSS1Z0LTBxdzRfZlN3cGc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGhnVUFkRVNoRjlmazJSSFA5ejRKR0E&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGhnVUFkRVNoRjlmazJSSFA5ejRKR0E&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGhnVUFkRVNoRjlmazJSSFA5ejRKR0E&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGhnVUFkRVNoRjlmazJSSFA5ejRKR0E&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGhnVUFkRVNoRjlmazJSSFA5ejRKR0E&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdFRSTGlJRnJSS1Z0LTBxdzRfZlN3cGc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdFRSTGlJRnJSS1Z0LTBxdzRfZlN3cGc&usp=sharing


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12a i) South (or S) ii) North (or N)

b The poles used to stroke the magnet is the same N-pole and X and Y cannot have the same S-pole.

13a Step 1: Fill up plastic bottle with a known volume of water.Step 2: Roll it down the plank and record time taken for bottle to roll from A to BStep 3: Repeat Step 1 and 2, two more times and find the average time.Step 4 : Conduct Step 1 to 3 but with a different volume of water

b The only variable she should change is the volume of wate r and all other variablesincluding the height of wooden plank must be kept the sam e.

14ai) Different metals expand at different rate.

a ii) Less. A t hicker rod has a greater mass so more heat is needed to make it expand to the samelength of 210mm

b) The bridge will deform/buckle/break because t here is no space for expansion to take place.

https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdG9pVDFENnB4VVlVRFRBSWkzdGlmcUE&usp=sharing

15a P: 3Q: 2

b i) 0.If B1 or B4 is fused, the circuit is opened and electricity cannot flow through a complete circuit.ii) 3.If either B2 or B3 is fused, electricity can still pass through 3 bulbs and the circuit is still closed.

16a When more water is added, mass/weight of test tube increase SO it sinks

b Remove/Release water from the tanks.

17a Place stone(stones) inside the water tank SO it can take up some space and lesser water is
https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdG9pVDFENnB4VVlVRFRBSWkzdGlmcUE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdG9pVDFENnB4VVlVRFRBSWkzdGlmcUE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdG9pVDFENnB4VVlVRFRBSWkzdGlmcUE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdG9pVDFENnB4VVlVRFRBSWkzdGlmcUE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdG9pVDFENnB4VVlVRFRBSWkzdGlmcUE&usp=sharing


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needed to fill the tank to level L

b Matter occupies space.

18a) Chemical potential energy of air in balloon is converted to kinetic energy when the air is released andat L, it was moving as it still has kinetic energy [1/2m] The car stops at M as all its kinetic energy has been converted to heat as it overcomes friction[1/2m ].

b) i) Inflate the balloon with more airii) Smoothen the surface of the floor by adding lubricant on top of it to reduce friction

19a The strength of the magnet is stronger at its ends than at its centre.

b Rod P.

Because it has a strong magnetic attraction at its ends with Q but a weaker force of attraction at

its middle .

20a Reason 1:- Larger exposed surface area- to increase the rate of evaporation

Reason 2:- Most of the water can drip down/away- less water left on plate to evaporate

b) Use a fan to speed up the rate of evaporation of water on plateshttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGx6WFF2ZXFwN0c1aWNEc0Q3VUVDUmc&usp=sharing

21a Q will be attracted to W [1] because when S2 is closed, W becomes an electromagnet [1] to attractQ

b The electric circuit where the fan is located is opened [1/2] SO electricity cannot flow throughthe fan . [1/2]
https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGx6WFF2ZXFwN0c1aWNEc0Q3VUVDUmc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGx6WFF2ZXFwN0c1aWNEc0Q3VUVDUmc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGx6WFF2ZXFwN0c1aWNEc0Q3VUVDUmc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGx6WFF2ZXFwN0c1aWNEc0Q3VUVDUmc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdGx6WFF2ZXFwN0c1aWNEc0Q3VUVDUmc&usp=sharing


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c He wanted to conserve electricity/energy [1/2]since both air conditioner and fan has the samepurpose of cooling the room .[1/2]

22a p135

There are

more air spaces/bigger gaps between the large sand particles than the small sandparticles. [1/2] SO

more water can flow through the air spaces/gaps and more water collected in A [1/2]

b The air spaces/gaps between the small sand particles is smaller SOlesser impurities can flow through and be collected in beaker

c No. There could be other impurities or germs smaller than the gaps that can make it through tothe beaker.

23a) P. P stretches more than Q for the SAME amount of load/weight attached to it. (must mention forSAME AMOUNTOF LOAD)

b) 4cm [1m]The spring has been over-stretched/over-extended hence an increase of 1cm from original length[1m]

[THIS IS ADEPENDENT QN;you must get thefirst part correct1st]

24a The longer the time, the lower the temperature will be

b For the same amount of time, temperature of set-up A decreases slower than set-up B

c - As air is an insulator/poor conductor of heat,- it reduces /minimises heat loss from the body to the surroundings

https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdHdlTnItU0htVjF3RG9nY0dXcDlZcnc&usp=sharing

25a Model B. It stays in the air the longest amount of time .

b Size of paper must be the same.
https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdHdlTnItU0htVjF3RG9nY0dXcDlZcnc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdHdlTnItU0htVjF3RG9nY0dXcDlZcnc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdHdlTnItU0htVjF3RG9nY0dXcDlZcnc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdHdlTnItU0htVjF3RG9nY0dXcDlZcnc&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdHdlTnItU0htVjF3RG9nY0dXcDlZcnc&usp=sharing


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26a It must be a good conductor of heat.

b i) Wire will melt.

ii) When wire melts, the circuit is opened [1/2] and electricity cannot flow through thecircuit.[1/2]

what qn

27a All the four magnets must be at the same height above the plastic tray.

b Observation 1:Magnet X is able to attract more pins than A from the same height

Observation 2:Magnet X is able to attract 4 pins(same number of pins) but at a higher height.

28a When the mist (made up of water droplets) gains heat from the surrounding air it evaporates to water vapour , and this causes the surrounding air to lose heat and temperature to fall/decrease.

b The fan produce/generates wind that speeds up the rate of evaporation

29a Material Q.It is able to reflect light the furth est (so anyone wearing the material at night can be seen from far)/can be seen from furthest distance

b Improves the accuracy and reliability of his experiment

https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDUtOGJFSHpybjYxbF9Xdkd1VVJmdEE&usp=sharing

30a) gravitational potential energy -> kinetic energy

b) Advantage: There will be more/greater electrical energy generated/produced when the height ofwater above turbine is mo re
https://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDUtOGJFSHpybjYxbF9Xdkd1VVJmdEE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDUtOGJFSHpybjYxbF9Xdkd1VVJmdEE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDUtOGJFSHpybjYxbF9Xdkd1VVJmdEE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDUtOGJFSHpybjYxbF9Xdkd1VVJmdEE&usp=sharinghttps://docs.google.com/spreadsheet/ccc?key=0AixrGoa_qU6rdDUtOGJFSHpybjYxbF9Xdkd1VVJmdEE&usp=sharing


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Explanation: Water a t a higher position has more gravitational potential energy [1/2] When it isreleased, more kinetic energy is produced to spin the turbine faster to generate more electricalenergy in the generator[1/2]

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Answer Key Physical Science