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Physics
NECO SSCE 2000
Heat Energy & Temperature
A piece of stone weights 180 N in air and 150 N in a beaker containing 160 N of methylated spirit. What is the up thrust exerted on the stone?
A
50N
B
40N
C
30N
D
20N
E
10N
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #42684)
Physics
NECO SSCE 2000
Modern Physics and Nuclear Physics
Solution
The half-life of a radioactive substance is 2 seconds. Calculate the decay constant.
A
2.890 s-1
B
1 .445 s-1
C
0.576 s-1
D
0.347s-1
E
0.152 s-1
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
\(T_{\frac{1}{2}} = \frac{\ln 2}{\lambda}\)
where \(T_{\frac{1}{2}}\) = half-life of element; \(\lambda\) = decay constant.
= \(\frac{0.693}{\lambda}\)
\(\therefore 2 = \frac{0.693}{\lambda}\)
\(\lambda = \frac{0.693}{2}\)
= 0.3465 s\(^{-1}\)
\(\approxeq\) 0.347 s\(^{-1}\)
Source: Myschool Past Questions Archive (Record #42685)
Physics
NECO SSCE 2000
Heat Energy & Temperature
Which of the following is used in a nuclear reactor to slow down fast moving neutrons?
A
graphite rods
B
carbon dioxide gas
C
liquid sodium metal
D
concrete shield
E
boron rods
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option A.
Source: Myschool Past Questions Archive (Record #42686)
Physics
NECO SSCE 2000
Mechanics and Properties of Matter
When electrical power is transmitted over long distances, the voltage is stepped up so that
A
the resistance of the wire may be increased proportionately to the potential difference
B
the time of transmissions between the generating and the receiving stations may be reduced
C
there is increased current to produce brighter lights.
D
the rate of electrical consumption is increased.
E
the energy waste may be minimised as the current is lowered.
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #42688)
Physics
NECO SSCE 2000
Mechanics and Properties of Matter
What is the coefficient of static friction between a load of mass 2kg and a horizontal surface, if the limiting frictional force is 10N? (g = 10 ms-2)
A
0.2
B
0.5
C
2
D
5
E
8
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #42693)
Physics
NECO SSCE 2000
Mechanics and Properties of Matter
When a lever is in equilibrium, under the action of two or more forces, the algebraic sum of the moments of the forces about the point of support is
A
anti-clockwise
B
clockwise
C
equal to the product to the forces
D
numerically equal to the total forces acting
E
equal to zero
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option E.
Source: Myschool Past Questions Archive (Record #42696)
Physics
NECO SSCE 2000
Thermal Physics
The specific heat of a substance in the solid state is C1; its specific beat in the liquid state is C2 and its latent heat of fusion is L. If a mass M of the substance is changed from the solid state at temperature T, to the liquid state, also at temperature T, the amount of heat required will be
A
M(C1 ÷ C2) x T
B
ML
C
L
D
M(C1 + C2) × T ÷ ML
E
ML(C1 + C2 ÷ 2) × T
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option B.
Source: Myschool Past Questions Archive (Record #42701)
Physics
NECO SSCE 2000
Modern Physics and Nuclear Physics
Solution
An element of nuclear number A and proton number Z emits an alpha particle from its nucleus. The nucleon number and the proton number of the new element formed are respectively
A
(A – 2) and (Z – 2)
B
(A + 4) and (Z + 2)
C
(A– 4) and (Z+2)
D
(A+ 4) and (Z – 2)
E
(A – 4) and (Z – 2)
medium Difficulty
Verified Correct Answer: Option E
Physical Principles & Numerical Solution
Let the element be S and the element formed after emission be X.
\(\implies ^{A} _{Z}S \to ^{4} _{2}He + X\)
\(\therefore X = ^{A - 4} _{Z - 2}X\).
Source: Myschool Past Questions Archive (Record #42704)
Physics
NECO SSCE 2000
Mechanics and Properties of Matter
The force exerted on a charged body in an electric field depends on
I. the charge on the body
II. the electric field intensity
III. the square of the mass of the body
A
I only
B
II only
C
I and II only
D
I and III only
E
II and III only
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option C.
Source: Myschool Past Questions Archive (Record #42710)
Physics
NECO SSCE 2000
Thermal Physics
Solution
400g of cold water is added to 200g of water at 70^\circC. If they are properly mixed and the temperature of the mixture is 30^\circC. calculate the initial temperature of the cold water. (Neglect the heat absorbed by the container)
A
10°C
B
15°C
C
20°C
D
30°C
E
40°C
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Heat lost by the warm water = heat gained by cold water
m\(_w\) X c X ( Tw - Tm) = m\(_c\) X c X (Tm - Tc)
200 X ( 70 - 30) = 400 X ( 30 - Tc)
2 x 40 = 120 - 4Tc
4Tc = 120 - 80 = 40
Tc = \(\frac{40}{4}\) = 10ºC
Source: Myschool Past Questions Archive (Record #42717)
Physics
NECO SSCE 2000
Heat Energy & Temperature
The heat from a fire in a closed room reaches someone far away in the room, mainly by
A
reflection
B
diffusion
C
conduction
D
radiation
E
convection
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
No expanded working has been attached for this question yet. The verified answer is Option D.
Source: Myschool Past Questions Archive (Record #42719)
Physics
NECO SSCE 2000
Mechanics and Properties of Matter
Solution
A solid weights 5.0 N in air, 4.2 N in water and 4.4 N in liquid Y. Calculate the relative density of liquid Y.
A
0.75
B
0.88
C
0.95
D
1.13
E
1.33
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
Given: Weight in air = 5.0 N, in water = 4.2 N, in liquid Y = 4.4 N.:
Loss of weight in Water: \( 5.0 - 4.2 = 0.8 \, \text{N} \)
Loss of weight in Liquid Y: \( 5.0 - 4.4 = 0.6 \, \text{N} \)
Relative density of liquid y
\(\text{RD}_{\text{Y}} = \frac{0.6}{0.8} = 0.75\)
The relative density of liquid Y is 0.75
Source: Myschool Past Questions Archive (Record #42722)
Physics
NECO SSCE 2000
Mechanics and Properties of Matter
Solution
Two forces forming a couple are separated by a distance of 25cm. If one of the forces equals 40N, what is the moment of the couple?
A
1000 Nm
B
500 Nm
C
10 Nm
D
5 Nm
E
1.6 Nm
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
The moment (or torque) of a couple is calculated by multiplying the size of one of the force by the perpendicular distance between the two forces.
Given: F = 40N; d = 25cm = 0.25m
Moment = 40 x 0.25 = 10Nm.
Source: Myschool Past Questions Archive (Record #42724)
Physics
NECO SSCE 2000
Modern Physics and Nuclear Physics
Solution
A radioactive substance has a half-life of 3 minutes. After 9 minutes, the count rate was observed to be 200. What was the count rate at zero time?
A
200
B
1200
C
1600
D
2400
E
4800
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Let the count at zero time = Q,
then count after 3s = \(\frac{Q}{2}\)
but after 9secs., count was observed to be = 200
count after 9secs = \(\frac{Q}{8}\) = 200 ( remember here, that we are dealing with half-life)
Q = 8 x 200 = 1600
∴ count at zero time = 1600.
Source: Myschool Past Questions Archive (Record #42727)
Physics
NECO SSCE 2000
Heat Energy & Temperature
Solution
Which of the following is NOT part of an a.c generator?
A
Commutator
B
Armature
C
Field magnet
D
Carbon brushes
E
Slip rings
medium Difficulty
Verified Correct Answer: Option A
Physical Principles & Numerical Solution
The general A.C. generator has all the listed components except the commutator.
Source: Myschool Past Questions Archive (Record #42729)