POST UTME CRAWFORD UNIVERSITY 2019 Physics | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A radioactive sample decays from 100 g to 50 g in 10 years. If the half-life of the sample is 5 years, calculate the decay cons\tant.
A. 0.01 yr^-1
B. 0.02 yr^-1
C. 0.03 yr^-1
D. 0.04 yr^-1
Question 2
A light ray passes through a prism with an apex angle of $60^{circ}$ and is re\fracted at an angle of $30^{circ}$. If the angle of incidence is $45^{circ}$, what is the angle of emergence?
A. $15^{circ}$
B. $30^{circ}$
C. $45^{circ}$
D. $60^{circ}$
Question 3
A \sinusoidal voltage source of amplitude $V_0$ and frequency $f$ is connected to a resistor of resis\tance $R$. If the voltage is measured at a time $t$, what is the voltage $V$?
A. V_0 \sin \( 2\pi ft \)
B. V_0 \cos \( 2\pi ft \)
C. V_0 \sin \( \pi ft \)
D. V_0 \cos \( \pi ft \)
Question 4
A block of mass 5 kg is moving with a velocity of 2 m/s on a frictionless surface. If a force of 10 N is applied to the block in the direction of motion, what is the acceleration of the block?
A. 0.2 m/s²
B. 0.4 m/s²
C. 0.6 m/s²
D. 0.8 m/s²
Question 5
A particle is moving in a circular path with a radius of 2 m. If the particle completes one revolution in 4 s, what is its angular velocity?
A. 1.57 rad/s
B. 3.14 rad/s
C. 6.28 rad/s
D. 12.56 rad/s
Question 6
A solid sphere of radius $R$ is placed in a liquid of density $\rho$ such that it is partially submerged. If the sphere has a density $\rho_s$ and the liquid exerts an upward buoyant force of $F_b$ on the sphere, what is the magnitude of the force $F$ exerted by the liquid on the sphere?
A. $F = F_b$
B. $F = F_b - \rho_s g V$
C. $F = F_b + \rho_s g V$
D. $F = \rho_s g V$
Question 7
A radioactive sample has a half-life of 10 years. If the initial activity is 100 Bq, what is the activity after 20 years?
A. 12.5 Bq
B. 25 Bq
C. 50 Bq
D. 100 Bq
Question 8
A particle is projected at an angle of 60° to the horizontal with an initial velocity of 20 m/s. If the acceleration due to gravity is 9.8 m/s², what is the time of flight?
A. 1.00 s
B. 1.50 s
C. 2.00 s
D. 2.50 s
Question 9
A circuit consists of a $10Omega$ resistor, a $20mu F$ capacitor, and a $50mH$ inductor connected in series. If the circuit is driven by a $10V$ AC source with a frequency of $100Hz$, what is the impedance of the circuit?
A. $10Omega$
B. $20Omega$
C. $30Omega$
D. $40Omega$
Question 10
A parallel plate capacitor has a capaci\tance of 10 μF. If a potential difference of 5 V is applied across the plates, what is the energy stored in the capacitor?
A. 25 μJ
B. 50 μJ
C. 75 μJ
D. 100 μJ
Question 11
A particle of mass 2 kg is attached to a spring with spring cons\tant 100 N/m. If the particle is displaced by 0.2 m from its equilibrium position and released from rest, what is the maximum speed of the particle?
A. 1.0 m/s
B. 2.0 m/s
C. 3.0 m/s
D. 4.0 m/s
Question 12
A 100 g block of copper is heated from 20°C to 80°C. If the specific heat capacity of copper is 0.385 J/g°C, what is the heat energy transferred?
A. 3.85 J
B. 4.15 J
C. 4.85 J
D. 5.15 J
Question 13
A photon of wavelength $\lambda$ and frequency $f$ is incident on a double-slit apparatus. The slits are separated by a dis\tance $d$. If the photon is detected at a dis\tance $x$ from the central maximum, what is the angle of deviation $\theta$?
A. \theta = \arc\sin \left\( \frac{\lambda}{d} \right \)
B. \theta = \arc\sin \left\( \frac{d}{\lambda} \right \)
C. \theta = \arc\cos \left\( \frac{\lambda}{d} \right \)
D. \theta = \arc\cos \left\( \frac{d}{\lambda} \right \)
Question 14
A lens of focal length $f$ is placed in a beam of light. The beam is incident on the lens at an angle $\theta$. If the lens is moved to a dis\tance $x$ from the original position, what is the new focal length $f'$?
A. \frac{f}{1 + \frac{x}{f}}
B. \frac{f}{1 - \frac{x}{f}}
C. \frac{f}{1 + \frac{f}{x}}
D. \frac{f}{1 - \frac{f}{x}}
Question 15
A particle of mass 2 kg is moving in a circular path of radius 3 m with a cons\tant speed of 4 m/s. If the particle is subjected to a centripetal acceleration of 2 m/s², what is the magnitude of the force acting on the particle?
A. 10 N
B. 12 N
C. 15 N
D. 18 N

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