# JAMB/WAEC/PTI Physics questions on Quantities, Unit, and Dimensions-2020 ## JAMB/WAEC/ PTI Physics questions: Quantities, Unit, and Dimensions

Quantities in physics are those things you can be measured. Meanwhile, this is part of the physics foundation. You might be faced with a physics problem that needs a solution. However, if the solution tends to be a number, let’s say 5. Well, telling someone that the answer is just 5, sound somehow. It can be 5 cars/books/phones. JAMB/WAEC/ PTI Physics questions

In physics, these things should be measured, and that’s where UNIT comes into play. Units give sense and meaning to your calculations. Telling someone that your answer is 5m(length of an object), makes more sense than just saying 5. Well, it will be more understandable when we give our results units. JAMB/WAEC/ PTI Physics questions

However, in Physics, there is three(3) kind of quantities and they include:

• Base/Fundamental Quantities,
• Derived Quantities,
• Supplementary Quantities.

So, let’s have a basic understanding of these Quantities.

### JAMB/WAEC/ PTI Physics questions: Fundamental Quantities

The fundamental quantities are quantities that can not be defined by other quantities. You can also say that they are independent of other Quantities. Below are some of the popular fundamental quantities and their units:

• Time – Seconds
• Length – Meter
• Mass – Kilogram
• Temperature – Kelvin
• Current – Ampere
• Amount of Substance – Mole
• Luminous Intensity – Candela JAMB/WAEC/ PTI Physics questions

## Derived Quantities

From its name, you can see that these Quantities are derived from other quantities. That is, they are dependent and defined from two or more fundamental quantities. Well, we all know about Speed. The unit of speed as we know is the meter(m) per second (s). Both meter and seconds are fundamental quantities. A combination of both will give you the unit of speed.JAMB/WAEC/ PTI Physics questions

## Supplementary Quantities

Well, this type of quantities ain’t that common. Meanwhile, in physics, we only recognize only two Supplementary Quantities and they include Plane angle and Solid angle. However, the International System of Units- S.I units are radians and steradian respectively.JAMB/WAEC/ PTI Physics questions

## Changing Units

In physics, we can change from one unit to another. This can be done through a Method known as chain- link conversion method. Here, all you have to do is to multiply the original measurement by a version factor. Meanwhile, this factor is usually of a ratio of one(1).

Remember the units of length. Which range from millimeters-centimeter-meter-kilometers. Well, knowing this conversion value can help you out with the chain-link conversion method. That’s 10mm makes 1cm and 100cm makes 1m. However, let’s say you need to convert 5m to cm. All you need to do is to multiply it by 100cm/1m and you get 500cm as your answer.JAMB/WAEC/ PTI Physics questions

## Dimension

The dimension of a physical quality is how they relate with the following: Mass(M), length(L), time(T) and current(I). JAMB/WAEC/ PTI Physics questions

Well, let take a look at some of the JAMB/WAEC/ PTI Physics questions on Quantities, Unit, and Dimensions.

## Possible JAMB/WAEC/ PTI Physics questions on Quantities, Unit, and Dimensions.

• 1. The instrument used for accurate measurement of the internal and external diameters of a pipe is the? (JAMB, 2016)

Ans: Vernier caliper.

• 2. What is the least possible error encountered when taking a measurement with a meter rule in millimeters? (JAMB, 2014)

Ans: 0.1mm

• 3. In order to remove the error of parallax when taking a measurement with a meter rule, the eye should be focused? (JAMB, 2012)

Ans: Vertically downwards on the markings.

• 4. The values of x, y, and z respectively in the expression { M }^{ x }{ L }^{ y }{ T }^{ z } for the universal gravitation constant G are?  (JAMB, 2009)

Ans. -1, 3, -2.

• 5. The dimension for electromotive force is?  (JAMB, 2008)

Ans: M{ L }^{ 2 }{ T }^{ -3 }{ I }^{ -1 }

• 6. The correct unit of energy density is? (JAMB,2006). Hint: energy density = force x distance/ volume

Ans: kg{ m }^{ -1 }{ s }^{ -2 }

• 7. A hose of cross-section area 0.5m’ is used to discharge water from a water tanker at a velocity of 60ms in the 20s into a container. If the container is filled completely, the volume of the container is? (JAMB, 2003)  hint: vol. = vel.x area x time

Ans: 600m

• 8. (i) force (N), (ii) torque (N { m }^{ -1 } ), (iii) current (A), (iv) power (W). Which of the above are the correct S.I units of the quantities indicated?

#### Ans: I, iii, and iv only.

• 9. Which of the following pairs consist of a fundamental quantity? A. Velocity and gravitational potential. B. Acceleration and field strength. C. Momentum and work-done. D. Moment and mass.

Ans: D

• 10. Which of the following quantities has the same unit as the product of pressure and volume of gas? A. Power. B. Acceleration. C. Work-done. D. Force.

Ans:

• 11. What is the dimensional unit of v in { v }^{ 2 } = { u}^{ 2} + 2as

Ans: L { T}^{ -1 }

• 12. Which of the following measurements is most precise? (a) 5.00 mm (b) 5.00 cm (c) 5.00 m (d) 5.00 km
• 13. U/1997/1  The values of x, y and z respectively in the expression for the universal constant G are (a) 2, -3, -2 (b) -1, 3, -2 (c) -1, 2, -3 (d) -2, -1, 3

#### SOLUTION

From Newton’s Law of gravitation

F=\frac { Gmm }{ { r }^{ 2 } }

making G the subject of the formula

G=\frac { {F} { r }^{ 2 } }{ mm}

in other word: G=\frac { {mass*acceleration} { r }^{ 2 } }{ mass*mass}

G=\frac { {MxL} { T}^{- 2 } }{ MxM}

Simplify G={ M }^{ -1 }{ L }^{ 3 }{ T }^{ -2 } Compare G={ M }^{ -1 }{ L }^{ 3 }{ T }^{ -2 } with { M }^{ x }{ L }^{ y }{ T }^{ z }x=-1, y =-3, z= -2 ans:B

• 14. U/2008/1 The dimensions of viscosity are (a) { M }^{ 2 }{ L T} (b){ M }{ L }^{ -1 }{ T }^{ -2 } (c) G={ M }^{ -1 }{ L }^{ -1 }{ T }^{ -1 } (d){ ML }{ T }^{ -1}

Ans: B

• I5. U/1993/1 Which of the following quantities has the same unit as the Watt? (a) Force x time (b) force x distance (c) force x acceleration (d) force x velocity

Ans: D

• 16. U/86/4 Which of the following is a derived unit? (a) kg (b) meter (c) Kelvin (d) Newton

Ans:

• 17. SSCE/1998/1 Which of the units of the following physical quantities are derived? () area () (IIl) pressure (IV) mass (a) I, II, IIl and Iv (b) I. II, and Ill only (c) I. II, and IV only (d) I and III only (e) I and IV only

#### SOLUTION

Only Mass is a fundamental quantity, others are derived I, II and III (B)

• 18. SSCE/1990/1 Which of the following instrument is suitable for making the most accurate measurement of the internal diameter of a test tube? (a) meter rule (a) a pair of calipers (c) a n neter screw gauge (d) a tape rule (e) a set square

SOLUTION A pair of calipers is most suitable B

• 19. U/98/1 The physical quantity that has the same dimensions as impulse is? (a) Energy (b) momentum (c) surface tension (d) pressure

SOLUTION Impulse = Change in momentum (B)

• 20. Poly/96/2 The dimensions of surface tensions are (a) { M }{ T}^{2}{L}^{-1} (b) { M }^{ -1 }{ L }^{ -1 }{ T }^{ 2 } (c) { M }{ T }^{ -2 } (d) { M }^{ -2 }{ T }^{ 2 }

Ans: C

#### JAMB/WAEC/ PTI Physics questions

• 21. UTME/1978/10 To determine the weight of an object, you could (a) use a beam balance (b) use a spring balance (c) find the force necessary give it a certain acceleration (d) use none of these methods (e) use any of these methods

SOLUTION Spring balance measure the weight of a body (B)

• 22.UTME/2007/45 The unit of moment of a couple is measured in (a) Nm (b) NmS (c) NS (d) J{S}^{ -1 }

SOLUTION  Moment= force(f) x distance (d) =Nxm= Nm (A)

• 23. UTME/2012/2 In order to remove the error of parallax when taking measurements with a meter rule, the eye should be focused (a) slanting towards the left on the markings (b) slanting towards the right on the markings (c) vertical downwards on the markings

#### SOLUTION

Error due to parallax is avoided when we view vertically downwards (C)

• 24. Which of the following instruments has a reading accuracy of 0.6mm? calipers of 0.6mm?

(a)  calipers vernier

(b) micrometer screw gauge

(c) meter  rule

(d) protractor

(e) spring balance

SOLUTION

micrometer has an accuracy of 0.01 mm or 0.001 cm

vernier caliper has accuracy of 0.lmm or 0.01cm

the meter rule has a readimg accuracy of a

5mm or 0.05cm (C)

25. SSCE/80/1 Which, of the following can be used to measure accuracy to three decimal places in centimeters? (a) meter rule (b) ruler (c) vernier caliper (d) micrometer screw gauge (e) none of the above

#### SOLUTION

Meter rule or ruler measure to 2dps

Vermier caliper measures to 2d.p in cm

Micrometer screw gauge measures to 3d.p in cm (D)

26. SSCE/2005/3 Which of the following statement about a spring balance and/or a chemical balance is NOT correct? (a) the chemical balance operates on Hooke’s law (b) the spring balance operates on Hooke’s law (c) Either maybe used to measure the weight of a substance (d) the reading of a spring balance changes over the surface of the earth, while that of the chemical balance remains constant

• 27. UTME/9 6/1 What is the percentage reading error in measuring a distance of 5.00cm using a meter rule marked in mm? (a) 10.0% (b) 5.0% (c) 1.0% (d) 50%

SOLUTION

lcm = 10mm

5.0cm = 50.0mm

Smallest division = Imm, reading error = 1/2

(Imm) = 0.5mm% error

=Smallest division x 100 /Actual measurment

0.5/50 *100 = 50*50=1.0%

• 28. UTME/1993/2 The external and internal diameters of a tube are measured as (32 ± 2) mm and (212 ± 1) mm respectively. Determine the percentage error in the thickness of the tube (a) 27% (b) 14% (c) 9% (d) 3%

SOLUTION Thickness = External diameter and internal diameter = (32 ± 2) – (21± 1) = ± 1

i.e (32 – 21) ± (21-1) = ± 1

error = ± 1,

Original thickness= 11

% error = error/original value X 100

1/11 x100 = 9.% (C)

• 29. PTIV2013/1 Which of the following is the diniension of acceleration? (a) LT (b)L {T}^{ -1} (c) {L}^{ 2}T (d) L {T}^{ 2} (e) L {T}^{ -2}

Ans: E

• 30. PTI/2013/3 The S.I unit of impulse is (a) N{S}^{ 2 } (b) NS (C) J{S}^{ -1 } (d) JS (e) watt

#### SOLUTION

Impulse = force (Newton) x time (s) =NxS= NS (B)

• 31. GCE A student measures the internal and external diameter of a cylindrical vessel as 100( ± 1)mm and104( ± 1)mm respectively. The possible error in the determination of the vessel is (a) ± 2mm (b) ± lmm (c) ± 0.5mm (d) Omm

SOLUTION The internal diameter could range from 99mm to 101mm and the external diameter from could  103mm to 105mm. the thickness could therefore range from (103 – 101) = 2mm to (105 – 99) = 6mm

i.e thickness will be measured as 4mm  ± 2mm error=i.e ± 2mm (A)

• 32. POST UTMEI/UNILAG/ The derived dimension {M }{ L }^{ 2 }{ T }^{ -2 } ? is a dimension of (T) acceleration (I) torque (III) energy (a) I only (b) II only (c) I and II only (d) II and III only

SOLUTION

M, L, T stand for mass length and time respectively.

Hence {M }{ L }^{ 2 }{ T }^{ -2 } = {M }{ L }{ T }^{ -2 } L

= (mass) (acceleration) (distance) = (force) (distance) which is the unit of torque or energy or work (D)

• 33. UTME The unit cycles per second is same as (a) watt (b) meters per second (c) hertz (d) radians per second

SOLUTION Cycles per second is the definition of frequency (hertz) = C

• 34. UTME The expression { M }^{ a }{ L }^{ b}{ T }^{ c } when a = 1, b=2 and C=2 is the dimension of (a) force (b) energy (c) acceleration (d) power

#### SOLUTION

Substitute a, b and c into { M }^{ a }{ L }^{ b}{ T }^{ c } { M }{ L }^{ 2}{ T }^{ -2} = (M) { L }{ T }^{ -2} (L)

=(mass) (acceleration) (distance) =(force) (distance) = work or energy (B)

• 35. UTME The most suitable instrument for measuring the diameter of a thin wire accurately is (a) a meter rule (b) a pair of vernier calipers (c) a micrometer screw gauge (d) a ruler

SOLUTION

Since the wire is thin, a micrometer screw gauge which is capable of measurements to the nearest 0.001 cm is most suitable (C)

• 36. SSCE Which of the following readings gives the correct precision of the length of a rod using a meter rule? (a) 75mm (b) 75.0mm  (c) 75.00mmn (d) 75.01mm

SOLUTION The smallest division on the mete rule is lmm; precise measurements can be made to the nearest 0.5mm  (c)

• 37. PTI The product PV where P is pressure and V is Volume has the same unit as (a) force (b) power (c) energy (d) acceleration

#### SOLUTION

PV =F/A x A x L= FL

FL= force x distance The unit will be joule which is energy

• 38. PTI/2001/1 Which of the following instruments is suitable for measuring the internal diameter of a test tube? (a) Meter rule (b) micrometer screw gauge (c) Vernier calipers (d) travelling  microscope (e) manometer.

Ans:

• 39. PTI/2001/2 Which of the following is a base unit? (a) candela (b) tesla (c) joule (d) Newton (e) farad

SOLUTION Base unit represent fundament unit (A)

• 40. PTI/2003/2 Which of the following reading is the most precise reading from a vernier caliper? (a) 3cm (b) 3.1cm (c) 3.255 cm (d) 3.250cm (e)  3.12cm

SOLUTION Vernier calipers measures to two decimal places in centimeters (E)

• 41. PTI/2007/1 The screw head carrying the circular scale in a micrometer screw gauge is turned through one complete revolution; it moves ____distance on the main scale (a) 0.05mm (b) 5mm (c) 50mm (d) 0.5mm (e) 0.0005mm

Ans:

•  42. PTIU2007/2 The difference in length between a vernier division and main scale in vernier calipers is (a) 0.01cm (b) 0.1cm (c) 0.01mm (d) 0.1m (e) 0.001cm

SOLUTION The correct option is (A)

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## 2 thoughts on “JAMB/WAEC/PTI Physics questions on Quantities, Unit, and Dimensions-2020”

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