CCC Hoh Fuk Tong College
First Term Examination 2007-2008
Physics
Section A - Multiple Choices (20 marks)
1 2 3 4 5 6 7 8
B B B A B C D B
11
A
12
D
13
C
14
A
15
D
16
A
17
D
18
A
9
C
19
D
2.
Section B - Questions (50 marks)
1. (a) Heat capacity = 2

1000 = 2000 J o C -1
(b) Energy required = 2000

80 = 160000 J
(c) Energy = 160000 + 5

4200

(100-20) (1)
= 160000 + 1680000
= 1840000 J (1)
(d) Energy wasted = 160000 J
(a) (i) Energy supplied = 60

(5

60) = 18000 J
(ii) c of metal = Ошибка!
= Ошибка!
= 360 J kg -1 ° C -1
(1)
(1)
(2)
(1)
(1)
(2)
(b) It is because some heat is lost to the surroundings .
Thus, the energy supplied is greater than the actual amount of energy absorbed by the metal. (2)
(c) Any one:

Wrap the metal block with an insulating material.
(1)

Grease the joints between the heater, thermometer and the metal block with oil or vaseline.
3. (a) 40 ° C (1)
10
D
20
C
page 1 of 4

5.
6.
4.
(b) Specific heat capacity = Ошибка!
= 4000 J kg -1 ° C -1
(c) The specific heat capacity at liquid state is higher because the slope of the graph at liquid state is less steep .
(d) L v
= Ошибка!
= 3.6

10 5 J kg -1
(2)
(2)
(2)
(a) Plastic is an insulator of heat .
Therefore, we can hold the plastic handle even though the water inside is very hot. (2)
(b) Hot water rises and cold water falls to set up a convection current.
Thus, the heater should be installed at the lowest position to heat cold water until it boils. (2)
(c) To reduce heat loss by radiation. (1)
(a) The target is to reduce emission of carbon-based gases to 5.2% lower than that in the 1990 level. (1)
(b) Major industrial countries
It will affect their economies.
(c) Decreasing area of crops.
(b)
Reduction in the living areas of people.
(a) Calm water provides a smooth reflectiong surface.
Regular reflection occurs at the water surface.
(2)
(2)
(2)
(1)
(1)
(1)
(1)
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7.
8.
9.
(b) plane mirror M
1
35 o
55 o 55 o
(0.5)
(0.5)
120 o
(1) plane mirror M
2
(0.5)
65 o
65 o
(0.5)
(1)
(a) i = 90 – 35 o
= 55 o
(b) Complete the path of the incident ray.
(c) Mark on it all angles of incidence and reflection.
(a) (i) By Snell's law: n x

sinx = n air

sin
 air
1.80

sin30 ° = 1

sin
 air
 air
= 64.2
°
(ii) C = sin
-1 Ошибка!
= sin
-1 Ошибка!
(1)
= 33.7
°
(1)
(a) slope = Ошибка!
= Ошибка!
= 1.55
(2)
The slope represents the refractive index of the glass .
(1)
(1)
(2)
(2)
(2)
(2)
(2)
(3)
page 3 of 4

(b) He is incorrect .
Total internal reflection does not occur when light travels from an optically less dense medium (air) to a denser medium (glass). (2)
～
～
page 4 of 4