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Physics
WAEC / WASSCE 2019
Thermal Physics
Solution
The wire of a platinum resistance thermometer has d resistance of 3.5\(\Omega\) at 0 ^\circC and 10.52\(\Omega\) at 100^\circC. Calculate the temperature of the wire when its resistance is 7.5\(\Omega\).
A
78 °C
B
25 \(^o\)C
C
30\(^o\)C
D
57 \(^o\)C
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
Using the formula
t = \(\frac{R - R_0}{R_{(100)} - R_0} \times 100^oC\)
t = \(\frac{7.5 - 3.5}{10.5 - 2..5} \times 100^oC\)
= \(\frac{4}{7} \times 100\)
= 57.14\(^o\)C
~ 57\(^o\)C
Source: Myschool Past Questions Archive (Record #58861)
Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
Solution
A transverse pulse of frequency 9 Hz traves 4.5m in 0.6 s. Calculate the wavelength of the pulse.
A
3.33 m
B
0.30 m
C
0.83 m
D
1.20 m
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Wavelength (\(\alpha\)) = \(\frac{Velocity (V)}{Frequency (f)}\)
Velocity = \(\frac{Distance}{Time}\) = \(\frac{4.5}{0.6}\)
= \(\frac{7.5}{9.0}\)
= 0.83m
Source: Myschool Past Questions Archive (Record #58863)
Physics
WAEC / WASSCE 2019
Waves and Optics
In which of the following media is the speed of sound the least?
A
Air
B
Brass
C
Water
D
Wood
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 #58885)
Physics
WAEC / WASSCE 2019
Heat Energy & Temperature
Which of the following statements about a moving object is correct?
A
When accelerating, the resultant force acting on it must be equal to zero.
B
There must always be a non-zero resultant force acting on it.
C
At a steady velocity, the resultant force acting on it must be equal to zero
D
At a steady velocity, the air resistance must be equal to zero.
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 #58822)
Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
Solution
If the efficiency of a transformer is 100%, which of the following equations would be correct?
A
N\(_p\)E\(_p\) = N\(_s\)E\(_s\)
B
N\(_s\)I\(_p\)= N\(_p\)I\(_s\)
C
N\(_s\)I\(_s\) = N\(_p\)I\(_p\)
D
I\(_p\)E\(_s\) = I\(_s\)E\(_p\)
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
For a transformer with 100% efficiency, the input power equals the output power:
E\(_p\)I\(_p\) = E\(_s\)I\(_s\)
Source: Myschool Past Questions Archive (Record #58844)
Physics
WAEC / WASSCE 2019
Heat Energy & Temperature
A freshly demagnetized bar magnet is placed in the East-West direction to ensure that
A
the molecular magnets remain randomly arranged.
B
the molecular magnets are properly aligned
C
it is affected by the earth's magnetic field
D
the magnetic domains are within the earth's field
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 #58845)
Physics
WAEC / WASSCE 2019
Electricity and Magnetism
Diagram
Solution
Which of the following graphs above of a charge Q against potential difference V across the capacitor is correct?
Attached Figure / Diagram
A
A
B
B
C
C
D
D
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
C = \(\frac{\text{Q}}{\text{V}}\) ⇒ Q = CV which means that Q Is directly proportional to V.
Source: Myschool Past Questions Archive (Record #58847)
Physics
WAEC / WASSCE 2019
Heat Energy & Temperature
A small amount of air is introduced into the vacuum above the mercury in a mercury barometer tube. The mercury level goes down because the air molecules
A
heat the mercury and make it expand
B
increase the pressure above the mercury.
C
cool the mercury and make it contract.
D
decrease the pressure above the mercury
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 #58848)
Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
Solution
A device consumes 100 W of power when connected to a 120 V source. Calculate its resistance.
A
1.2\(\Omega\)
B
12,000 \(\Omega\)
C
20.0\(\Omega\)
D
144\(\Omega\)
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
P = \(\frac{V^2}{R}\)
R = \(\frac{120^2}{100}\)
= 144.0\(\Omega\)
Source: Myschool Past Questions Archive (Record #58985)
Physics
WAEC / WASSCE 2019
Thermal Physics
The anomalous expansion of water occurs in the range
A
0 °C to 100 °C
B
0 °C to 4 °C
C
4 °C to 100 C
D
-4 °C to 0 °C
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 #59014)
Physics
WAEC / WASSCE 2019
Thermal Physics
Solution
A rectangular piece of iron measuring 4 cm by 3 cm at 20\(^o\)C is heated until its temperature increases by 100 C. Calculate the new area of the metal. [Linear expansivity of iron is 1.2x 10\(^{-5}\) K\(^{-1}\)]
A
12.0144 cm\(^3\)
B
12.0346 cm\(^3\)
C
12.0288 cm\(^3\)
D
12.0173 cm\(^3\)
medium Difficulty
Verified Correct Answer: Option C
Physical Principles & Numerical Solution
Linear expansivity (\(\alpha\))
= \(\frac{A_2 - A_1}{A_1\theta}\)
Original Area(A\(_1\)) = 4 x 3 = 12
New Area (A\(_2\)) = ?
Temp. rise (\(\theta\)) = 100\(^o\)C
A\(_2\) - 12 = 1200 x 2 x 1.2 x 10\(^{-5}\)
A\(_2\) - 12 = 2880 x 10\(^-5\)
A\(_2\) - 12 = 0.0288
A\(_2\) = 12.0288 cm\(^2\)
Source: Myschool Past Questions Archive (Record #59017)
Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
Diagram
Solution
Which of the following graphs gives the correct relationship between energy and mass when mass is converted to energy.
Attached Figure / Diagram
A
A
B
B
C
C
D
D
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Energy is directly proportional to mass when mass is converted to energy. According to Albert Einstein’s mass-energy equivalence formula:
E = mc\(^2\)
Source: Myschool Past Questions Archive (Record #58889)
Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
Solution
An 800 kg car moving at 80 km hr\(^{-1}\) collides with a 1200 kg car moving at 40 km hr\(^{-1}\) in the same direction. If the cars stick together, calculate their common velocity.
A
60 km hr\(^{-1}\)
B
8 km hr\(^{-1}\)
C
40 km hr\(^{-1}\)
D
56 km hr\(^{-1}\)
medium Difficulty
Verified Correct Answer: Option D
Physical Principles & Numerical Solution
From momentum conservation
(800 x 80) + (1200 x 40)
= (800 + 1200) V
= 64000 + 48000 = 2000V
112000 = 2000V
V = \(\frac{112000}{2000}\)
= 56kmh\(^-1\)
The common velocity = 56kmhr\(^{-1}\)
Source: Myschool Past Questions Archive (Record #58901)
Physics
WAEC / WASSCE 2019
Mechanics and Properties of Matter
Solution
The mass of a load is doubled while the force acting on it is halved. The resulting acceleration of the load is
A
quadrupled
B
quartered
C
halved
D
doubled
medium Difficulty
Verified Correct Answer: Option B
Physical Principles & Numerical Solution
Force = mass x acceleration
but force was halved = 1/2 and mass doubled = 2 ( assuming that force and mass are 1N and 1kg respectively)
f = ma = \(\frac{1}{2}\) = 2 x a
dividing both sides by 2
a = \(\frac{1}{2} \times\frac{1}{2} = \frac{1}{4}\)
Source: Myschool Past Questions Archive (Record #58904)
Physics
WAEC / WASSCE 2019
Thermal Physics
The maximum and minimum thermometer reads the
A
the maximum temperature during the day and the minimum temperature at night at all times.
B
the maximum temperature at night and minimum temperature during the day from the last reset
C
the maximum temperature at night and minimum temperature during the day at all times
D
the maximum temperature during the day and minimum temperature at night from the last reset
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 #58913)