Mye 2006 Answers

Secondary 4 Mid-Year Examinations 2006 Answers Paper 1 (MCQ) 1.

B

11.

D

21.

C

31.

B C B

2. B 3. A

12. B 13. A

22. A 23. C

32. 33.

4. 5. 6. 7.

14. A 15. C 16. C 17. B

24. A 25. B 26. D 27. A

34. B 35. C 36. A 37. B

18. 19. 20.

28. 29. 30.

38. 39. 40.

C C C D

8. B 9. D 10. A

C D C

D B C

D D C

PAPER 2 – SECTION A (50 marks) Section A A1. a) zero error = - 0.02mm or –0.002cm b)

Actual thickness of coin = 1.19mm/0.199cm – (-0.02mm)/(-0.002cm) = 1.21mm or 0.121cm

c)

The results obtained will be less accurate/inaccurate as the force used to close the screw gauge each time is inconsistent .

A2. a)

Acceleration is the rate of change of velocity.

b) Acceleration is decreasing with time until it reaches zero at t = 5.0s c)

It can be applied to an object that is dropped from a height. Speed starts at zero. Acceleration decreases as air resistance increases with speed. Acceleration reaches zero when air resistance is equal to weight of object/downward force OR when terminal velocity is reached.

A3. Density of gold chain = 88.7/5.8 = 15.3 g/cm3 (3sf) or 15 g/cm3 (2sf) Conclusion: chain is not made of pure gold A4. a)

Spring balance/force balance

b) taking moments about B total clockwise moments = total anti-clockwise moments tension x AB = weight x GB tension x 0.9 = (0.800kg x 10) x (0.9 - 0.7) tension = 1.8 N (2sf) or 1.78 N (3 sf) c)

There will be no effect/ the value will not change. There are no changes to the perpendicular distances from the line of action of the two forces to the pivot. / Or AG and AB remain constant.

A5. a)

The rate at which water flows out of the tap depends on water pressure. On the ground floor, the water pressure is higher compared to a higher floor. OR On a higher floor, the water pressure is lower compared to the ground floor.

b)

When room temperature is increased, the molecules gain kinetic energy/move faster. They collide more frequently and violently with the walls of the container. This force exerted on the walls of the container increases and hence pressure increases.

A6. ai)

In general, speed increases as wavelength increases.

aii)

Speed remains constant when depth changes.

aiii)

frequency = speed/wavelength = 9.33/100 = 0.0933 Hz/ 9.33x10-2 Hz

b)

Place the ping pong ball in the water and observe its motion. The ping pong ball should bob up and down at the same location. This shows that the water molecules are not moving along with the waves but only vibrates about in a vertical plane. Hence, the waves are transverse waves.

A7. a) b)

The angle of incidence is zero. The angle of incidence of the light in the block is greater than critical angle. Total internal reflection occurs.

ci) O A Correct ray with arrow Marking and labeling of B

G

Figure 7.3 cii)

A8. a)

B

X

angle AOB = tan-1 (AB/OA) = tan-1 (1.68/1.50) = 48.240º (at least 5sf) critical angle, C = 180º - 48.240º - 90º = 41.760º refractive index = 1/sin C = 1.50 (3sf) The electrons are transferred from the cloth to the rod This causes the rod to be negatively charged as it has more/extra electrons.

b)

The copper rod is a conductor in which electrons are free to move. The extra charges gained from the cloth will be transferred to the hand.

c)

Hold on to the copper rod with an insulator instead of using bare hands.

d)

Nothing will happen. Copper is a non-magnetic material and it will not be affected by the magnet.

A9. a)

Yes. The current running through the wire set up a magnetic field.

bi)

The field lines for magnet A are closer compared to the field lines for magnet B/ The field lines for magnet A extend further than the field lines for magnet B.

bii)

They will experience the same force of attraction. The two forces form an action-reaction pair/The forces of attraction are caused by the interaction of both magnetic fields. Hence, they will be the same.

Section B B1. ai) Result A blow of hot air A blow of cold air

Switch A √

Switch B √ √

Switch C √ √

aii)

C

aiii)

The heat generated by the heater would not be effectively removed. This may cause the exterior cover of the dryer to melt.

aiv)

The live components inside a hair dryer are carefully shielded and isolated from the user by means of double insulation. Hence, the assessible metal parts cannot become live unless the two independent layers of insulation fail at the same time. OR The outer casing of the hair dryer is made of insulator There is no danger of the casing becoming live.

b)

pd across ammeter = IR = 0.6 x 5.0 = 3V total current through PQ = V/Reff = 3/(1/5.0 + 1/0.10)-1 = 30.6A OR From V= IR, I is proportional to 1/R Inew / Iold = Rold / Rnew Inew = (5.0/ (1/5.0 + 1/0.10)-1) x 0.6 = 30.6A The ammeter is only reading part of the current that flows through PQ. The total current flowing through the resistor is greater than 3A, hence it will blow.

B2) ai)

As water around the coil gets cooled, it sinks as density increases while warmer water rises to take its place. This sets up a convection current which can remove heat from the bottom of the beaker effectively.

aii)

As A is at the top of the beaker, it can only be cooled down by conduction. /convection cannot take place As water is a bad conductor, it will be cooled down slowly.

aiii)

Water has the highest density at 4ºC. Hence it will remain at the bottom of the beaker even as the rest of the water continues to cool down.

b)

Energy required to melt the ice = ml = 0.25 x 336000 = 84000 J Energy required to raise the temperature of water = mcθ = 0.25 x 4200 x 20 = 21000 J Total energy required = 84000 + 21000 = 105000 J

c)

Either B3) ai)

aii)

The energy is used to break the bonds between the molecules/ The energy is used to overcome the attractive forces between the molecules/ The energy is used to increase the potential energy of the molecules/ It is used to change the state of water.

Difference in pressure = 150mmHg = (150x10-3)(13600)(10) Pa = 20400 Pa Pressure at the point = atmospheric pressure + pressure due to mercury = (1.0 x 105) + (5x10-2)(13600)(10) = 16800 Pa

aiii) As water has a low density, the column would be very long. bi) Using ‘v = fλ’ λ=v/f = 1600/24000 = 0.067 m (2sf) or 0.0667 m (3sf) bii) No effect. The speed of the wave depends on the medium which is not changed. OR B4) ai) aii)

KE = ½ x m x v2 = ½ x 0.300 x 9.82 = 14.4 J GPE gained = mgh = 0.300 x 10 x 2.3 = 6.9 J

aiii)

Total energy at L = KE at L + GPE at L = 14.4 + 0.3 x 10 x 1.5 = 18.9J

aiv)

Total energy at M = KE at M + GPE at M = ½ x 0.3 x 52 + 0.3 x 10 x 3.8 = 15.2J (3sf) No. Air resistance should not be ignored because energy is lost to overcome it.

bi)

This is to magnify the reading/ to act as a magnifying glass.

bii)

Make the capillary tube thinner. For the same change in volume, the change in the length of the mercury tube is more. OR Make the bulb larger. For the same temperature change, the change in the length of the mercury tube is more.

biii) The thermometer will have a shorter/narrower/smaller range.