Practice Post UTME BELLS UNIVERSITY physics 2018 Past Questions

Question 1

A particle of mass $m$ is moving in a circular path of radius $r$ with a cons\tant speed $v$. The particle experiences 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{mv^2}{r}

Correct C. \frac{4mv^2}{r}

D. \frac{mv^2}{2r}

Correct Answer: C

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Question 2

A capacitor consists of two parallel plates, each of area $A$ and separation $d$. The capacitor is charged to a potential difference $V$ and then disconnected from the power source. If the plates are then brought together to a separation of $d/2$, what is the new potential difference $V_{new}$?

Correct A. \frac{V}{2}

B. \frac{3V}{2}

C. \frac{V}{4}

D. \frac{3V}{4}

Correct Answer: A

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Question 3

A block of mass $m$ is placed on a frictionless surface and attached to a horizontal spring with a spring cons\tant $k$. The block is displaced by a dis\tance $x$ from its equilibrium position and released from rest. What is the maximum speed $v_{max}$ of the block as it oscillates?

A. \sqrt{\frac{kx^2}{m}}

Correct B. \sqrt{\frac{2kx^2}{m}}

C. \sqrt{\frac{3kx^2}{m}}

D. \sqrt{\frac{4kx^2}{m}}

Correct Answer: B

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Question 4

A parallel plate capacitor consists of two plates, each of area $A$ and separation $d$. The capacitor is charged to a potential difference $V$ and then disconnected from the power source. If the plates are then brought together to a separation of $d/2$, what is the new capaci\tance $C_{new}$?

Correct A. \frac{C}{2}

B. \frac{3C}{2}

C. \frac{C}{4}

D. \frac{3C}{4}

Correct Answer: A

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Question 5

A block of mass $m$ is placed on a frictionless surface and attached to a horizontal spring with a spring cons\tant $k$. The block is displaced by a dis\tance $x$ from its equilibrium position and released from rest. What is the period $T$ of the block's oscillation?

Correct A. \frac{2\pi}{\sqrt{k/m}}

B. \frac{2\pi\sqrt{k/m}}

C. \frac{\pi}{\sqrt{k/m}}

D. \frac{\pi\sqrt{k/m}}

Correct Answer: A

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Question 6

A gas is heated from 300 K to 400 K at cons\tant volume. What is the ratio of the final pressure to the initial pressure?

Correct A. 1.33

B. 1.5

C. 2

D. 3

Correct Answer: A

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Question 7

A sound wave with a frequency of 200 Hz has a speed of 340 m/s. What is the wavelength of the sound wave?

Correct A. 1.7 m

B. 1.8 m

C. 1.9 m

D. 2 m

Correct Answer: A

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Question 8

A light ray passes from air into a glass block with a re\fractive index of 1.5. If the angle of incidence is 30°, what is the angle of re\fraction?

A. 20°

Correct B. 22°

C. 25°

D. 28°

Correct Answer: B

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Question 9

A force of 10 N is applied to an object, cau\sing it to accelerate at 2 m/s². What is the mass of the object?

A. 5 kg

Correct B. 10 kg

C. 15 kg

D. 20 kg

Correct Answer: B

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Question 10

A car travels from rest to a speed of 25 m/s in 5 s. What is the average power developed by the car?

A. 125 W

Correct B. 250 W

C. 375 W

D. 500 W

Correct Answer: B

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Question 11

A parallel plate capacitor has plates of area 0.04 m^2 and separation 0.02 m. If the capaci\tance is 8 nF, what is the value of the dielectric cons\tant?

Correct A. 1.25

B. 2.5

C. 5

D. 10

Correct Answer: A

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Question 12

A ray of light passes from air into a glass slab of re\fractive index 1.5. If the angle of incidence is 30°, what is the angle of re\fraction?

Correct A. 20°

B. 30°

C. 40°

D. 50°

Correct Answer: A

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Question 13

A particle moves in a circular path with a cons\tant speed of 5 m/s. If the radius of the path is 2 m, what is the centripetal acceleration?

A. 2.5 m/s^2

Correct B. 5 m/s^2

C. 10 m/s^2

D. 20 m/s^2

Correct Answer: B

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Question 14

A 100 V AC supply is connected across a 50 Ω resistor. If the frequency of the supply is 50 Hz, what is the rms value of the current?

A. 2 A

Correct B. 4 A

C. 6 A

D. 8 A

Correct Answer: B

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Question 15

A 2 kg object is moving in a straight line with a velocity of 4 m/s. If a force of 10 N is applied in the same direction, what is the acceleration?

A. 2 m/s^2

Correct B. 4 m/s^2

C. 6 m/s^2

D. 8 m/s^2

Correct Answer: B

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Question 16

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 acceleration of the particle?

A. 2 m/s^2

B. 4 m/s^2

Correct C. 6 m/s^2

D. 8 m/s^2

Correct Answer: C

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Question 17

A 100 W light bulb is connected to a 220 V power source. If the resis\tance of the bulb is 10 Ω, what is the current flowing through the bulb?

A. 0.5 A

Correct B. 1 A

C. 2 A

D. 4 A

Correct Answer: B

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Question 18

A convex lens of focal length 20 cm is used to form an image of an object placed 30 cm away from the lens. What is the magnification of the image?

A. 1

Correct B. 2

C. 3

D. 4

Correct Answer: B

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Question 19

A parallel plate capacitor has a capaci\tance of 10 μF and is charged to a potential difference of 12 V. If the dis\tance between the plates is doubled, what is the new capaci\tance?

A. 5 μF

Correct B. 10 μF

C. 20 μF

D. 40 μF

Correct Answer: B

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Question 20

A 2 kg object is moving in a circular path with a cons\tant speed of 4 m/s. If the radius of the path is doubled, what is the new speed of the object?

A. 2 m/s

B. 4 m/s

Correct C. 6 m/s

D. 8 m/s

Correct Answer: C

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Question 21

A uniform magnetic field of strength 2 T is applied to a coil of wire with 100 turns. The coil has a radius of 0.05 m and a resis\tance of 5 Ω. If the current in the coil is 2 A, what is the induced emf?

A. 0.1 V

B. 0.2 V

Correct C. 0.5 V

D. 1 V

Correct Answer: C

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Question 22

A 12 V battery is connected to a 4 Ω resistor in series with a 6 Ω resistor. What is the current in the circuit?

A. 0.8 A

Correct B. 1.2 A

C. 1.6 A

D. 2 A

Correct Answer: B

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Question 23

A 100 W bulb is connected to a 230 V power supply. What is the resis\tance of the bulb?

A. 200 Ω

B. 400 Ω

Correct C. 529 Ω

D. 800 Ω

Correct Answer: C

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Question 24

A 10 g sample of radioactive material decays to 5 g in 10 minutes. What is the half-life of the material?

A. 10 minutes

Correct B. 20 minutes

C. 30 minutes

D. 40 minutes

Correct Answer: B

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Question 25

A 2 kg block is attached to a horizontal spring with a force cons\tant of 100 N/m. The block is displaced by 0.1 m from its equilibrium position and released from rest. What is the maximum speed of the block?

A. 0.2 m/s

B. 0.3 m/s

Correct C. 0.5 m/s

D. 0.6 m/s

Correct Answer: C

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