Physics 2024 Jamb Examination
Physics 2024 Jamb Examination
Question 51
What will be the weight of a man of mass 60kg standing in a lift if the lift is descending vertically at 3ms\(^2\)?
When a lift descends with an acceleration \( a \), the apparent weight (\( R \)) of a person is less than their true weight (\( mg \)). The formula is:
\[ R = m(g - a) \]
Assuming \( g = 10\,ms^{-2} \):
\[ R = 60(10 - 3) \]
\[ R = 60(7) = 420\,N \]
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Question 52
The gravitational force between two objects masses 10\(^{24}\)kg and 10\(^{27}\)kg is 6.67N. Calculate the distance between them [ G = 6.6 x 10\(^{-11}\) Nm\(^2\)kg\(^{-2}\) ]
Using Newton's Law of Universal Gravitation:
\[ F = \frac{G m_1 m_2}{r^2} \]
\[ r^2 = \frac{G m_1 m_2}{F} \]
\[ r^2 = \frac{(6.6 \times 10^{-11}) \times 10^{24} \times 10^{27}}{6.67} \]
\[ r^2 \approx 10^{40} \]
\[ r = \sqrt{10^{40}} = 1.0 \times 10^{20}\,m \]
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Question 53
The tangential force acting on an object that opposes it from sliding freely on the adjacent surface is called
Friction is the force that resists the relative motion of solid surfaces. It acts tangentially to the surface of contact and in a direction opposite to the direction of motion or intended motion.
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Question 54
Two tuning forks of frequencies 6Hz and 4Hz respectively are sounded together. The beat frequency is
The beat frequency is simply the absolute difference between the frequencies of the two sound sources.
\[ f_{beat} = |f_1 - f_2| \]
\[ f_{beat} = 6\,Hz - 4\,Hz = 2\,Hz \]
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Question 55
The capacitance of a capacitor, C, is inversely proportional to
The capacitance of a parallel-plate capacitor is given by:
\[ C = \frac{\delta A}{d} \]
Where \( A \) is the area of the plates and \( d \) is the distance between them. This formula shows that \( C \) is inversely proportional to the distance \( d \).
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Question 56
The value of R in the circuit to make the galvanometer measure 2A is
To convert a galvanometer into an ammeter, a shunt resistor \( S \) is connected in parallel. Using typical JAMB values:
\[ S = \frac{I_g R_g}{I - I_g} \]
\[ S = \frac{0.01 \times 25.5}{2 - 0.01} \approx 0.128\,\Omega \]
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Question 57
An object is placed 25cm in front of a convex mirror has its image formed 5cm behind the mirror. what is the focal length of the convex mirror
Using the mirror formula: \( \frac{1}{f} = \frac{1}{u} + \frac{1}{v} \).
For a convex mirror, the image is virtual, so \( v \) is negative. \( u = 25\,cm \), \( v = -5\,cm \) \[ \frac{1}{f} = \frac{1}{25} + \frac{1}{-5} = -\frac{4}{25} \] \[ f = -6.25\,cm \]
For a convex mirror, the image is virtual, so \( v \) is negative. \( u = 25\,cm \), \( v = -5\,cm \) \[ \frac{1}{f} = \frac{1}{25} + \frac{1}{-5} = -\frac{4}{25} \] \[ f = -6.25\,cm \]
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Question 58
In a Hare's apparatus, the height of water and a liquid X are 0.3m and 0.5m respectively. The relative density of x is?
Hare's apparatus is used to compare densities:
\[ h_w \rho_w g = h_x \rho_x g \]
\[ \text{Relative Density of } X = \frac{h_w}{h_x} = \frac{0.3}{0.5} = 0.6 \]
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Question 59
The quantity of heat required to melt ice of 0.2 kg whose specific latent heat is 3.4 x 10\(^5\) J/Kg is
The heat \( Q \) required for phase change is:
\[ Q = mL = 0.2 \times (3.4 \times 10^5) = 6.8 \times 10^4\,J \]
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Question 60
I. It wets glass; II. It needs to be coloured; III. It has a low density. Water is not suitable for use as a thermometric liquid because
Water is unsuitable because it wets glass, is transparent, and has a non-linear expansion (anomalous expansion at 4°C). [Image comparing mercury and water in thermometer tubes]
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