# Physics 2008 | Study Mode

Question 11
A
steam condeses and occupies the partial vacuum in the can
B
external air pressure counter balances the pressure within the can
C
steam expands to occupy the vacuum remaining in the can
D
external pressure becomes greater than the pressure within the can.
##### Explanation
Cold water reduces the temperature of the hot water inside the can causing the contraction of the hot water. This reduces the pressure inside the can and the can collapses due to the external greater expression.

Question 12
A
(1)/3
B
(2)/3
C
(1)/5
D
(2)/5
##### Explanation
relative density = (weight of substance )/weight of equal volume of water = (4 - 2)/5 - 2 = (2)/3

Question 13
A
equivalent resistance
B
electromotive force
C
colour
D
pressure
##### Explanation
Temperature difference between hot and cold junctions of thermocouple is proportional to the emf. generated

Question 14
A
the clock gians time
B
the accuracy of the clock is not affected
C
the clock losses time
D
the clock stops working
##### Explanation
The elastic potential energy of the balance wheel reduces as the wheel expands, therefore the clock will loose time.

Question 15
A
508 cm3
B
516 cm3
C
608 cm3
D
616 cm3
##### Explanation
V1 = 600cm3, T1 = 27 = 273 = 300k
T2 = 35 + 273 = 308K, V2 = ?
(V)1/T1
= (V)2/T2 = V2
= (V)1/T1 x X T2
= (600 X 308)/300 = 616 cm3

Question 16
A
850 JK-1
B
750 JK-1
C
650 JK-1
D
500 JK-1
##### Explanation
Heat supplied = Heat gained
P x t = C
(25 x 5 x 60)/300 = 750 JK-1

Question 17
A
25%
B
33%
C
75%
D
82%
##### Explanation
Relative
Humidity = (S.V.P. of water at dew point)/S.V.P of water at air temperature =(18)/24 x 100% = 75%

Question 18
A
conduction through the cork
B
the plastic base of the thermos flask
C
the silvered walls and shiny metals
D
the outer cover or jacker
##### Explanation
Since the cork is in contact with the walls of the flask, little conduction takes place

Question 19
A
12.4 m
B
15.7 m
C
17.5 m
D
18.6 m
##### Explanation
Comparing y = 5sin (200 t - 0.4X) with the wave equation y = A sin (wt -KX) K = (2)/ = 0.4
= (2)/0.4 = 15.7M

Question 20
A
wavelength
B
harmonies
C
frequency
D
velocity
##### Explanation
Timber/ quality depends on the overtones or harmonics, and timber is a characteristic property of source of sound.

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