POST UTME UNN 2021 Physics | Objective

Practice these randomly selected questions to test your readiness.

Question 1
A spring of spring cons\tant $k$ is stretched by a dis\tance $x$. If the spring is then released, determine the maximum speed of the spring.
A. \( \sqrt{\frac{kx^2}{m}} \)
B. \( \frac{kx^2}{m} \)
C. \( \frac{kx}{m} \)
D. \( \frac{k}{m} \)
Question 2
A projectile is launched from the ground with an initial velocity of 20 m/s at an angle of 30° above the horizontal. If air resis\tance is neglected, what is the maximum height reached by the projectile?
A. 10 m
B. 15 m
C. 20 m
D. 25 m
Question 3
A wave has a frequency of 50 Hz and a wavelength of 0.2 m. What is the speed of the wave?
A. 10 m/s
B. 20 m/s
C. 30 m/s
D. 40 m/s
Question 4
A circuit consists of a resistor $R$, an inductor $L$, and a capacitor $C$ connected in series. The circuit is driven by an AC voltage source with a frequency $f$. If the inductive reac\tance $X_L = 10\,\Omega$ and the capacitive reac\tance $X_C = 5\,\Omega$, what is the impedance $Z$ of the circuit?
A. \sqrt{R^2 + \( X_L + X_C \)^2}
B. \sqrt{R^2 + \( X_L - X_C \)^2}
C. \sqrt{R^2 - \( X_L - X_C \)^2}
D. \sqrt{R^2 + \( X_L + X_C \)^2}
Question 5
A 2 kg object is moving in a circular path of radius 4 m with a cons\tant speed of 3 m/s. If the object is subjected to a centripetal force of 8 N, what is the magnitude of the force?
A. 12 N
B. 16 N
C. 20 N
D. 24 N
Question 6
A particle moves in a circular path with a cons\tant speed of 5 m/s. If the radius of the circle is 2 m, what is the magnitude of the acceleration of the particle?
A. 10 m/s^2
B. 20 m/s^2
C. 30 m/s^2
D. 40 m/s^2
Question 7
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 force of 12 N, what is the magnitude of the force?
A. 16 N
B. 12 N
C. 24 N
D. 32 N
Question 8
A charged particle of mass $m$ and charge $q$ is moving in a uniform magnetic field of strength $B$ with a velocity $v$. If the particle experiences a force $F$ due to the magnetic field, determine the magnitude of the force.
A. \( qvB \sin \theta \)
B. \( qvB \cos \theta \)
C. \( qvB \)
D. \( qvB \sin \theta \cos \theta \)
Question 9
A circuit consists of a 10 Ω resistor and a 20 Ω resistor connected in series. If a voltage of 12 V is applied across the circuit, what is the current flowing through the circuit?
A. 0.4 A
B. 0.6 A
C. 0.8 A
D. 1.0 A
Question 10
A block of mass $m$ is attached to a horizontal, massless spring with a spring cons\tant $k$. The block is displaced by a dis\tance $x$ from its equilibrium position and released from rest. Assuming the block undergoes simple harmonic motion, what is the maximum speed $v_{max}$ of the block?
A. \frac{kx}{m}
B. \sqrt{\frac{kx^2}{m}}
C. \frac{kx^2}{m}
D. \frac{mx^2}{k}
Question 11
A particle of mass 2 kg is moving in a circular path of radius 4 m with a cons\tant speed of 6 m/s. Determine the magnitude of the force acting on the particle.
A. \( 12 , \text{N} \)
B. \( 15 , \text{N} \)
C. \( 18 , \text{N} \)
D. \( 20 , \text{N} \)
Question 12
A photon of energy $E$ is incident on a metal surface with work function $\phi$. If the photon is absorbed by the metal, determine the maximum kinetic energy of the emitted electron.
A. \( E - \phi \)
B. \( E + \phi \)
C. \( E \phi \)
D. \( \phi - E \)
Question 13
A uniform magnetic field of strength 2 T is applied to a current-carrying wire of length 0.5 m. If the current in the wire is 5 A, calculate the force experienced by the wire.
A. 0.5 N
B. 1 N
C. 2 N
D. 5 N
Question 14
A body of mass 5 kg is moving with a velocity of 10 m/s. Determine the kinetic energy of the body.
A. \( 50 , \text{J} \)
B. \( 60 , \text{J} \)
C. \( 70 , \text{J} \)
D. \( 80 , \text{J} \)
Question 15
A particle of mass $m$ is moving in a circular path of radius $r$ with a cons\tant speed $v$. The particle is subject to a centripetal force $F_c$ given by $F_c = \frac{mv^2}{r}$. If the particle's speed is doubled to $2v$, what is the new centripetal force $F_{c,new}$?
A. \frac{2mv^2}{r}
B. \frac{4mv^2}{r}
C. \frac{mv^2}{2r}
D. \frac{mv^2}{4r}

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