ANSWER JULY TEST PHYSICS FORM 4 2011

Objective questions

1. C 11. D

2. C 12. A

3. D 13. B

4. D 14. D

5. B 15. B

6. B 16. C

7. C 17. A

8. C 18. D

9. A 19. A

10. C 20. B

Subjective questions

1. a) Force per unit area. b) Water pressure = hpg

= 1000 × 9.8 × 3 @ 1000 × 10 × 3 = 29 400 Nm2 or 30 000 Pa.

c) The water pressure at Q is higher than the water pressure at P / The depth at Q is higher than the depth at P. This is because the pressure in a water increases when the depth of the liquid increases.

2. a) (i) The air molecules move at a lower speed. (ii) The air pressure becomes smaller / decreases. (iii) The air pressure in the bottle is lower than the atmospheric pressure outside of it. As a result, a net force acts on the bottle from outside.

3. a) Atmospheric pressure is a pressure cause by the force exerted by a thick layer of air which is the weight of the atmosphere on Earth’s surface.

b) (i) 0 or zero pressure. (ii) 75 cm Hg. (iii)

Pressure = 75 – 60 = 15 cm Hg = (15/100) × 13.6×103 ×10 [hpg] = 2.04 × 104 Pa

Or Patm = Pgas + Phg

Atmospheric pressure = gas pressure + mercury pressure 75 = Pgas + 60

Pgas = 75 – 60

4. a) Finput = Foutput

Ainput Aoutput

Foutput = Finput × Aoutput

Ainput

= 120 × 128 16 = 960 N

b) Pascal’s principle c) The system can convert a small input force into a bigger output force. d) The movement of the output piston will be slowed down and reduced because the air inside the cylinder will be compressed by the input force. 5.

a) (i) In the figure above.(ii) Buoyant force = Weight

b) Archimedes’ principlec) (i) Buoyant force = Apparent weight loss

(ii) Buoyant force = 10 - 8 = 2 N

Buoyant force

Weight