JAMB UTME - Physics - 1987 | Green Bridge CBT

Pregunta 1 Informe

A boat at anchor is rocked by waves whose crest are 100m apart and whose velocity is 25ms-1. At what interval does the wave crest reach the boat?

2500.00s

75.00s

4.00s

0.25s

Detalles de la respuesta

Distance between the boat and crest = 100m

time = $\frac{100}{25}$

= 4sec

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Pregunta 2 Informe

When the length I of a piece of wire under constant tension is varied, the relationship of the frequency of the vibration $ \alpha $/ is

f

α

/

f

α \frac{1}{I^{2}}

f

α \sqrt{I}

f

1

Detalles de la respuesta

F =

\frac{1}{2 L} \sqrt{\frac{T}{m}}

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Newton’s Laws Of Motion

Equilibrium Of Forces

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Pregunta 3 Informe

What type of reaction is represented by the following scheme?

\[ {}^{2}_{1}X + {}^{2}_{1}Y + {}^{3}_{2}Z + {}^{1}_{0}n + \text{energy} \]

Fusion reaction

Fission reaction

Chain reaction

Radioactive decay

Elementary Modern Physics

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Pregunta 4 Informe

When two parallel wires carry currents in opposite directions, the force on either wire is

away from the other wire

zero, because the currents cancel each other

twice as much as when the currents are in the same direction

towards the other wire

Newton’s Laws Of Motion

Equilibrium Of Forces

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Pregunta 5 Informe

The velocity time graph above describes the motion of a particle between two points P and Q. What is the distance between P and Q?

17.0m

18.0m

22.5m

30.0m

Motion

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Pregunta 6 Informe

A wave has a frequency of 2Hz and a wavelength of 30cm. The velocity of the wave is

60.0ms-1

6.0ms-1

1.5ms-1

0.6ms-1

Detalles de la respuesta

V = F

λ

= 2 x 0.3

= 0.6ms-1

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Production And Propagation Of Waves

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Pregunta 7 Informe

In which of the following are the substance arranged in descending order of their thermal conductivities?

copper, steel, glass

steel, copper, glass

steel, glass, copper

copper, glass, steel

Heat Transfer

Fluid At Rest

Gravitational Field

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Pregunta 8 Informe

If a beaker is filled with water it is observed that the surface of the water is not horizontal at the glass-water interface. This behavior is due to

friction

viscosity

surface tension

evaporation

Friction

Temperature And Its Measurement

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Pregunta 9 Informe

The fig above represents the main sequence of energy conversion at Kainji dam. What is the efficiency of the system?

Q1/Q2

E/Q1

E/(Q1-Q2)

E/(Q1+Q2)

Heat Energy

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Pregunta 10 Informe

A man walks 8km north and then 5km in a direction 60o east of north. Find the distance from his starting point

11.36km

12.36km

13.00km

14.36km

Detalles de la respuesta

R =

\sqrt{5^{2} + 8^{2} - 2 \times 5 \times 8 \times c o s 120^{o}}

R = $\sqrt{129}$

= 11.36km

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Scalars And Vectors

Position, Distance And Displacement

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Pregunta 11 Informe

A cube of side 10cm and mass 0.5kg floats in a liquid with only $ \frac{1}{5} $ of its height above the liquid surface. What is the relative density of the liquid?

0.125cm-1

0.250gcm-1

0.625cm-1

2.500cm-1

Detalles de la respuesta

Height below liquid = 1 -

\frac{1}{5}

=

\frac{4}{5}

volume of cube = 103cm3

volume of liquid displaced = $\frac{4}{5}$ x 1000

= 800cm3

density of liquid displaced;

= $\frac{500}{800}$

= 0.625cm-1

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Light Energy

Simple Harmonic Motion

Quantity Of Heat

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Pregunta 12 Informe

Which of the following instruments has a pure tone?

guitar

vibrating strings

tuning fork

siren

Sound Waves

Work, Energy And Power

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Pregunta 13 Informe

As a result of air at the top of a barometer, the height of the mercury column is 73.5cm when it should be 75.0cm; the volume of the space above the mercury is 8.0cm3. Calculate the correct barometer height when the barometer reads 74.0cm and the volume of the space above the mercury is 6.0cm3.

72.0cm

74.5cm

75.1cm

76.0cm

Detalles de la respuesta

Using, P1P1 = P2P2

(75 - 73.5) x 8 = (X - 74) x 6

X = 76cm

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Pressure

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Pregunta 14 Informe

A 50kg block is dropped from a point 10cm above as shown in the fig above. if the force constant of the spring is 4.0 x 104Nm-1, find the maximum compression of the spring [g = 10ms-2]

1.25m

0.50m

0.25m

0.05m

Equilibrium Of Forces

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Pregunta 15 Informe

The length of a side of a metallic cube at 20oC is 5.0cm. Given that the linear expansivity of the metal is 4.0 x 10-5k-1, find the volume of the cube at 120oC .

126.50cm3

126.25cm3

126.00cm3

125.00cm3

Detalles de la respuesta

Y =

\frac{V_{2} - V_{1}}{V_{1} \times θ}

3 x 4 x 10-5 = $\frac{V_{2} - 125}{125 \times (120 - 20)}$

V2 = 126.50cm3

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Temperature And Its Measurement

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Pregunta 16 Informe

A load of 5N gives an extension of 0.56cm in a wire which obeys Hooke's law. What is the extension caused by a load of 20N?

1.12cm

2.14cm

2.24cm

2.52cm

Detalles de la respuesta

\frac{F_{1}}{e_{1}}

=

\frac{F_{2}}{e_{2}}

$\frac{5}{0.56}$ = $\frac{20}{e_{2}}$

e2 = 2.24cm

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Elasticity

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Pregunta 17 Informe

A radioactive sample initially contains N atoms. After three half-lives the number of atoms that have disintegrated is

N

8

3N

8

5N

8

7N

8

Detalles de la respuesta

N

\to

\frac{N}{2}

\to

\frac{N}{4}

\to

\frac{N}{8}

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Temperature And Its Measurement

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Pregunta 18 Informe

If an object is placed in front of two mirrors inclined at 90o, how many images will be formed?

five

four

three

two

Detalles de la respuesta

n =

\frac{360}{θ}

- 1

= 360 - 1

= 3 images

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Electrostatics

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Pregunta 19 Informe

he lowest note emitted by a stretched string has a frequency of 40Hz. How many overtones are there between 40Hz and 150Hz?

1

2

3

4

Detalles de la respuesta

In stretched strings the overtones are in odd multiple of Fo.

F1 = 3Fo

= 3 x 40 = 120Hz

F2 = 5Fo

= 5 x 40

= 200Hz

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Propagation Of Sound Waves

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Pregunta 20 Informe

A galvanometer of resistance $20\,\Omega$ is to be provided with a shunt that $\frac{1}{10}$ of the whole current in a circuit passes through the galvanometer. The resistance of the shunt is

2.00

Ω

2.22

Ω

18.00

Ω

18.22

Ω

Detalles de la respuesta

\frac{1}{10}

I x 20 =

\frac{9}{10}

I x Rs

Rs = 2.22 $Ω$

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Electrostatics

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Pregunta 21 Informe

An elevator of mass 4800kg is supported by a cable which can safely withstand a maximum tension of 60 000N. The maximum upward acceleration the elevator can have is

2.5ms-2

5.0ms-2

7.5ms-2

10.0ms-2

Detalles de la respuesta

a =

\frac{F}{m}

= $\frac{60000 - (4800 \times 10)}{4800}$

= 2.5ms-2

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Newton’s Laws Of Motion

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Pregunta 22 Informe

A current of 0.5A flows through a resistor when connected to a 40-V battery. How much energy is dissipated in 2 minutes?

1200J

1500J

2400J

96000J

Detalles de la respuesta

Electrical energy = IVT

= 0.5 x 40 x 2 x 60

= 2400J

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Current Electricity

Work, Energy And Power

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Pregunta 23 Informe

A pool of water appears to be 1.0m deep when viewed vertically from above. If the refractive index of water is 1.33, what is the actual depth of the pool?

0.750m

1.013m

1.330m

13.3000m

Detalles de la respuesta

n =

\frac{real depth}{apparent depth}

1.33 = $\frac{real depth}{1}$

real depth = 1.33cm

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Refraction Of Light Through Plane And Curved Surfaces

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Pregunta 24 Informe

Which of the following phenomena explains the fact that a house whose roof is coated with white paint will be cooler in the hot season than one coated with black paint ?

conduction

convection

refraction

reflection

Pressure

Simple A.C Circuits

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Pregunta 25 Informe

The direction of the magnetic field at a point in the vicinity of a bar magnet is

always towards the north pole of the magnet

always away from the south pole of the magnet

along the line joining the point to the neutral point

in the direction the north pole of a compass needle would point

Magnetic Field (Part 1)

Electromagnetic Field (Part 2)

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Pregunta 26 Informe

The fig above shows two connected bodies of masses M1 and M2 in equilibrium under gravity. The tension in the upper string is

(m1-m2)g

m1g

m2g

(m1+m2)g

Equilibrium Of Forces

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Pregunta 27 Informe

In the figure above, M and N are insulated metal spheres in contact. A negatively charged ebonite rod P is I brought near M. When M and N are Separated and the rod is taken away, which of the following statements is correct

both M and N have acquired negative charges

both M and N have acquired positive charges

M has acquired negative charge and N positive charge

N has acquired negative charge and M positive charge

Electrostatics

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Pregunta 28 Informe

The mechanical advantage (MA) of an inclined plane depends on

its length

its height

the product of its length and height

the ratio of its length to its height

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Pregunta 29 Informe

The vacuum in a thermos flask helps to reduce heat transfer by?

convection and radiation

convection and conduction

conduction and radiation

radiation only

Heat Transfer

Temperature And Its Measurement

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Pregunta 30 Informe

22,000J of heat is required to raise the temperature of 1.5kg of paraffin from 20oC to 30oC. Calculate the specific heat capacity of paraffin.

1466Jkg-1oC-1

2933Jkg-1oC-1

4400Jkg-1oC-1

5866Jkg-1oC-1

Detalles de la respuesta

22,000 = 1.5 x c x (30 - 20)

c = 1466Jkg-1oC-1

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Heat Energy

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Pregunta 31 Informe

Hot water is added to three times its mass of water at 10oC and the resultant temperature is 20oC. What is the initial temperature of the hot water?

100oC

80oC

50oC

40oC

Detalles de la respuesta

Heat loss = heat gained

mh x ch x $θ$ h = mc x cc x $θ$ c

mh x ch x ( $θ$ - 20) = mc x cc x (20 - 10)

ch = cc ; mc = 3mh

therefore, $θ$ = 50oC

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Temperature And Its Measurement

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Pregunta 32 Informe

When a transformer has more secondary windings than primary windings, it

has a smaller secondary current

has a greater power output

is a step-down transformer

increases the total energy output

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Pregunta 33 Informe

Which of the following statements is TRUE of photoelectric effect?

it cannot occur in liquids

the energy of the emitted electrons is independent of the work function of the surface

the energy of the emitted electron depends on the wavelength of the incident light

the greater the intensity of the incuident light, the greater the incident of the emitted electron

Structure Of The Atom (Nigeria Only)

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Pregunta 34 Informe

In the above, a voltage V is applied across the terminals P and Q. The voltage across the 1 ohm resistor is

V/8

V/4

V/3

V/2

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Pregunta 35 Informe

A body rolls down a slope from a height of 100m. its velocity at the foot of the slope is 20ms-1. What percentage of its initial potential energy is converted into kinetic energy? [g = 10ms-1]

40%

35%

20%

15%

Detalles de la respuesta

P.E = mgh = 1000m joules

K.E = $\frac{1}{2}$ mv2 = 200m joules

%converted = $\frac{200 m}{1000 m}$ x 100

= 20%

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Measurements And Units

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Pregunta 36 Informe

If the angle of declination in a place is 10oE, calculate the true geographic bearing if the compass reads N40oE

N50oE

N40oE

N30oE

N25oE

Speed And Velocity

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Pregunta 37 Informe

Calculate the amount of heat required to convert 2kg of ice at 2oC to water at 0oC. [specific heat capacity of ice = 2090Jkg-1oC-1, specific latent heat of fusion of ice = 333kJkg-1]

666J

8360J

666 000J

674 360J

Detalles de la respuesta

Q = mL + mc

θ

= (2 x 333000) + (2 x 2090 x 2)

= 674 360J

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Quantity Of Heat

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Pregunta 38 Informe

A constant force of 40N acting on a body initially at rest gives an acceleration of 0.1ms-2 for 4s. Calculate the work done by the force

8J

10J

32J

160J

Detalles de la respuesta

X = ut +

\frac{1}{2}

at2

= (0 x 4) + ( $\frac{1}{2}$ x 0.1 x 4 x 4)

= 0.8m

workdone = force x distance

= 40 x 0.8

= 32J

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Work, Energy And Power

Equilibrium Of Forces

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Pregunta 39 Informe

he coefficient of static friction between a 40kg crate and concrete surface is 0.25. Find the magnitude of the minimum force needed to keep the crate stationary on the concrete base inclined at 45o to the horizontal. [G = 10ms-1]

400N

300N

283N

212N

Detalles de la respuesta

momentum force = R5n

θ

-

μ

Rcos

θ

Fm = (40 x 10 x sin 45) - (40 x 10 x 0.25 x cos 45)

= 212N

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Friction

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Pregunta 40 Informe

Which of the following units is equivalent to kgms-1?

Ns-1

Nms-1

Ns

Js-1

Detalles de la respuesta

kgms-1 =

\frac{m a s s}{d i s t a n c e}

since, F = ma = kgms-1 = N

kgms-1 = Ns

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Measurements And Units

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Pregunta 41 Informe

The distance between the fixed points of a centigrade thermometer is 20cm. What is the temperature when the mercury level is 4.5cm above the lower mark?

22.5oC

29.0oC

90.0oC

100.0oC

Detalles de la respuesta

20cm .... 100oC

4.5cm .... $θ$

0cm ....0oC

$\frac{4.5 - 0}{20 - 0}$ = $\frac{0 - 0}{100 - 0}$

$θ$ = 22.5oC

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Temperature And Its Measurement

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Pregunta 42 Informe

An object 3.0cm high is placed 60.0cm from a converging lens whose focal length is 20.0cm. Calculate the size of the image formed

0.5cm

1.5cm

2.0cm

6.0cm

Detalles de la respuesta

F =

\frac{U V}{U + V}

20 = $\frac{60 \times V}{60 + V}$

V = 30cm

similarly, $\frac{U}{V}$ = $\frac{height of object}{height of image}$

$\frac{60}{30}$ = $\frac{3}{h}$

h = 1.5cm

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Light

Measurements And Units

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Pregunta 43 Informe

Which of the following statements supports the assumption that light travels in straight lines?

light can be diffracted

a source of light produces distinct shadows of opaque objects

a source of light produces interference patterns on a suitably placed screen

light can be reflected

Light Energy

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Pregunta 44 Informe

A jet engine develops a thrust of 270Ns when the velocity of the exhaust gases relative to the engine is 300ms-1. What is the mass of the material ejected per second?

81.00kg

9.00kg

0.90kg

0.09kg

Detalles de la respuesta

Thrust = force x time

thrust = $\frac{m (v - u)}{t}$ x $\frac{t}{1}$

270 = m(300 - 0)

m = 0.90kg

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Measurements And Units

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Pregunta 45 Informe

Two capacitance of $6\,\mu\text{F}$ and $8\,\mu\text{F}$ are connected in series. What additional capacitance must be connected in series with this combination to give a total of $3\,\mu\text{F}$

3

μ

F

16

μ

F

24

μ

F

30

μ

F

Detalles de la respuesta

3 =

\frac{6 \times 8 \times c}{(6 \times 8) + (6 \times c) + (8 \times c}

therefore, C = 24 $μ$ F

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Capacitors

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Pregunta 46 Informe

Isotopes are nuclei which have

the same number of nuetrons and electrons

equal number of electrons and protons

the same atomic number but different number of neutrons

the same number of total particles

Structure Of The Atom (Nigeria Only)

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Pregunta 47 Informe

A ray of light is incident at an angle of 30o on one top surface of a parallel-sided glass block of refractive index 1.5. The ray finally emerges from the lower surface. What is the angular deviation of the emergent ray?

60o

39o

28o

0o

Reflection Of Light At Plane And Curved Surfaces

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Pregunta 48 Informe

Four lenses are being considered for use as a microscope objective. Which of the following focal lengths is most suitable?

-5mm

+5mm

-5cm

+5cm

Electromagnetic Waves: Types Of Radiation In Electromagnetic Spectrum

Light Waves

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