07 AL Physics/M.C./P.3
2007 Hong Kong Advanced Level Examination
AL Physics
Multiple Choice Questions (Solution)
07 AL Physics/M.C./P.3
1. D
The system is in equilibrium state
Þ S F = 0
Þ The force vectors form a closed triangle (as shown in the figure)
rod P: in tension
rod Q: in compression
2. A
consider the wedge and the mass as a whole system, since the mass slides down the wedge with constant velocity, the total vertical force acting on the system = 0. Hence, the normal reaction exerted by the ground on the wedge = total weight of the system, i.e. (M + m)g.
3. C
moving up: accelerating downwards, a > g
at the highest point: a = g
moving down: accelerating downwards, a < g
hence, slope of the v – t graph (i.e. acceleration) should decrease with time.
4. B
vertical: L cos 21.8° = mg
horizontal: L sin 21.8° =
hence, tan 21.8° =
v =
= 200 ms-1
5. A
6. B
Period of oscillation = 4 ´ 4 = 16 s
Hence, after 14 s the particle passes X the third time.
7. C
8. A
9.
10. B
d sin q = ml
d sin 45° = 3l
d/l = 3/sin 45°
= 4.2
hence, the highest order is 4
11. C
Dy =
d = =
= 4.4 ´ 10-4 m
12. A
v = -5 cm
magnification = v/u = 0.5
13. B
14. B
E-field, E µ 1/r2
EX = 72 units
=
EY = 36 units
15. C
e = vlB
I µ l
16.
17.
18. D
FPQ = FPS =
FPR =
=
=
I’ = 2I
19.
F = ilB^
7.5 ´ 10-5 = 8 ´ 0.5 ´ B cos 20°
B = 2.0 ´ 10-5 T
20.
21.
22. D
e = NBAw
= NwF
=
= 8.0 V
23.
24.
N =
=
=
=
3 =
3 =
T = 18 days
25.
26.
27.
=
v =
Escape velocity:
=
v = =
since the launching speed 2v is greater than the escape velocity, the spacecraft would leave the earth and travel to outer space.
28. B
By Kepler’s 3rd law,
= const.
=
r = 61R
29. B
(1) Incorrect: The rope is heavy and the weight is not negligible. Tension at the point near the top end of the rope should be greater while that near the bottom end should smaller.
(2) Incorrect: the frequency of oscillation must be the same for all vibrating points of the rope. Wave speed v, which depends on the tension, varies from point to point along the rope. Hence, the wavelength is not the same throughout the rope.
(3) Correct
30. A
light intensity after passing through P = I/2
light intensity after passing through Q = = I/8
31.
32. C
= Df
= Df
= 5
c = 321 ms-1
33.
34.
35.
07 AL Physics/M.C./P.3