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Unilorin Post-UTME Physics 2021 (Model questions) past questions and answers

10 questions. Try each one, then open the answer to check yourself and read the explanation.

Question 1

Structure of Matter and Kinetic Theory

Which of the following observations is not an effect of surface tension?

  1. A.Droplets of water dripping slowly from a tap
  2. B.Mercury spilled on a clean glass plate forms small spherical droplets
  3. C.An insect walking across the surface of a pond
  4. D.Water flowing out more easily than engine oil from a container
Show the answer and explanation

Answer: D (Water flowing out more easily than engine oil from a container)

Explanation

Water flowing out faster than oil is about viscosity (oil is more viscous), not surface tension.

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Question 2

Measurement and Units

Which of the following physical quantities is correctly paired with its corresponding SI. unit?

  1. A.Density [kgm3]
  2. B.Power [Js−1]
  3. C.Specific latent heat [J kg−1 K−1]
  4. D.Pressure [N m−1]
Show the answer and explanation

Answer: B (Power [Js−1])

Explanation

Power is energy per second, J s−1 (the watt). Density is kg m−3, latent heat J kg−1 and pressure N m−2.

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Question 3

Density and Upthrust

A liquid of volume 2.00m3 and density 1.00 x 103kgm−3 is mixed with 3.00 m3 of another liquid of density 8.00 x 102 kg m−3. Calculate the density of the mixture. [Assume there is no chemical reaction].

  1. A.5.20 x 102 kg m−3
  2. B.8.80 x 102kg m−3
  3. C.1.13 x 103kg m−3
  4. D.5.20 x 103 kgm−3
Show the answer and explanation

Answer: B (8.80 x 102kg m−3)

Explanation

Masses: 2 × 1000 = 2000 kg and 3 × 800 = 2400 kg. Density = 4400 kg ÷ 5 m3 = 880 kg m−3 = 8.80 × 102 kg m−3.

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Question 4

Friction

Which of the following statements about solid friction are correct? It I. is a force. II. occurs between the surfaces of two bodies in contact. III depends on the area of contact.

  1. A.I and II only
  2. B.I and III only
  3. C.II and III only
  4. D.II and III
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Answer: A (I and II only)

Explanation

Friction is a force acting between surfaces in contact, but solid friction does not depend on the area of contact.

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Question 5

Newton's Laws and Momentum

A man of mass m, experiences a viscous drag, F and an upthrust U as he descends towards the ground at a steady velocity, using a parachute. If the acceleration of free fall is g, which of the following expressions is correct?

  1. A.FU = mg
  2. B.U+F−mg=0
  3. C.U−F=mg
  4. D.F−U−mg=0
Show the answer and explanation

Answer: B (U+F−mg=0)

Explanation

At steady velocity the net force is zero: the upward forces U and F balance the weight mg, so U + F − mg = 0.

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Question 6

Motion

A body moving at a constant speed accelerates when it is in

  1. A.rectilinear motion.
  2. B.translational motion.
  3. C.circular motion.
  4. D.vibrational motion.
Show the answer and explanation

Answer: C (circular motion.)

Explanation

In circular motion the direction keeps changing, so the velocity changes and the body accelerates even at constant speed.

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Question 7

Motion

An object of mass 2 kg moves with a uniform speed of 10 ms−1 for 5 s along a straight path. Determine the magnitude of its acceleration.

  1. A.0ms−2
  2. B.1ms−2
  3. C.3ms−2
  4. D.4ms−2
Show the answer and explanation

Answer: A (0ms−2)

Explanation

Uniform speed in a straight line means the velocity does not change, so the acceleration is zero.

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Question 8

Motion

The term, rectilinear acceleration means the rate of increase of

  1. A.velocity along a circular path in a unit time.
  2. B.distance along a rectangular path in a unit time.
  3. C.displacement along a straight-line path in a unit time.
  4. D.velocity along a straight-line path in a unit time.
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Answer: D (velocity along a straight-line path in a unit time.)

Explanation

Rectilinear means along a straight line, and acceleration is the rate of change of velocity.

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Question 9

Motion

A vehicle moving with a uniform speed is gradually brought to rest. Which of the following sketches describes le motion of the vehicle?

Diagram for this question
  1. A.Sketch A
  2. B.Sketch B
  3. C.Sketch C
  4. D.Sketch D
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Answer: B (Sketch B)

Explanation

The graph must be flat (uniform speed) and then slope down steadily to zero speed, which is sketch B.

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Question 10

Motion

A body moving with an initial velocity u accelerates until it attains a velocity of v within a time t. The distance, covered by the body is given by the expression

  1. A.s = ((v − u)/2)t
  2. B.s = ((v + 2u)/2)t
  3. C.s = ((v + u)/2)t
  4. D.s = ((2v + u)/2)t
Show the answer and explanation

Answer: C (s = ((v + u)/2)t)

Explanation

With uniform acceleration, distance = average velocity × time = ((u + v)/2)t.

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