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JAMB UTME - Physics - 1985

Vraag 1 Verslag

Two thermo flasks of volume \(V_x\) and \(V_y\) are filled with liquid water at an initial temperature of 0^oC. After sometime the temperature were found to be \(\theta_x\), \(\theta_y\), respectively. Given that \(\frac{V_x}{V_y}=2\) and \(\frac{\theta_x}{\theta_y}=\frac{1}{2}\) the ratio of the heat flow into the flask is

1

4

1

2

4

1

2

Antwoorddetails

Heat = mc

θ

Hx = Dx x Vx x Cx x $θ$ x

Hy = Dy x Vy x Cy x $θ$ y

$\frac{H_{x}}{H_{y}}$ = $\frac{D_{x} \times V_{x} \times C_{x} \times θ_{x}}{D_{x} \times V_{x} \times C_{x} \times θ_{x}}$

= 2 x $\frac{1}{2}$

= 1

Lees lesnotitie op Quantity Of Heat (JAMB)

Quantity Of Heat

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Vraag 3 Verslag

Two rays of light from a point below the surface of water are equally inclined to each other at \(60^\circ\) in water. What is the angle between the rays when they emerge into air? (Take the refractive index of water to be \(\frac{4}{3}\))

41.8o

44.1o

60.0o

83.6o

120.0o

Antwoorddetails

\frac{4}{3}

=

\frac{s i n r_{1}}{s i n 30}

and

\frac{4}{3}

=

\frac{s i n r_{2}}{s i n 30}

r1 = 41.8o and r2 = 41.8o

angle between them = r1 + r2

= 83.6o

Lees lesnotitie op Refraction Of Light Through Plane And Curved Surfaces (JAMB)

Refraction Of Light Through Plane And Curved Surfaces

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Vraag 5 Verslag

Two divers G and H are at depths 20m and 40m respectively below the water surface in a lake. The pressure on G is P₁ while the pressure on H is P₂. If the atmospheric pressure is equivalent to 10m of water, then the value of \( \frac{p_2}{p_1} \) is

0.50

0.60

1.67

2.00

3.0

Antwoorddetails

pressure at H = 40m ; pressure at G, p1 = 20m

$\frac{p_{1}}{p_{1}}$ = $\frac{40}{20}$

= 2

Lees lesnotitie op Temperature And Its Measurement (JAMB)

Lees lesnotitie op Pressure (JAMB)

Lees lesnotitie op Measurements And Units (JAMB)

Temperature And Its Measurement

Measurements And Units

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Vraag 6 Verslag

A uniform cylindrical block of wood floats in water with one-third of its height above the water level, in a liquid of relative density 0.8, what fraction of its height will be above the liquid level?

1

6

1

5

1

3

4

5

\frac{5}{6}

Antwoorddetails

Height inside H2O =

\frac{2}{3}

R.d = $\frac{height inside H_{2} O}{height inside liquid}$

0.8 = $\frac{\frac{2}{3}}{X}$

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Vraag 8 Verslag

A metal block of mass 5kg lies on a rough horizontal platform. If a horizontal force of 8N applied to the block through its center of mass just slides the block on the platform, then the coefficient of limiting friction between the block and platform is

0.16

0.63

0.80

1.60

2.00

Antwoorddetails

F =

μ

R

= $μ$ mg

8 = $μ$ x 5 x 10

$μ$ = 0.16

Lees lesnotitie op Friction (JAMB)

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Vraag 10 Verslag

If a car starts from rest and moves with a uniform acceleration of 10ms-2 for ten seconds, the distance it covers in the last one second of its motion is

95m

100m

500m

905m

1000m

Antwoorddetails

Distance in 105, using, x = ut +

\frac{1}{2}

at2

x = (0 x 10) + ( $\frac{1}{2}$ x 10 x 10 x 10) = 500m

distance in 9s; x - (0 x 9) + ( $\frac{1}{2}$ x 10 x 9 x 9) = 405m

distance in last is = difference

= 500 - 405

= 95m

Lees lesnotitie op Motion (JAMB)

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Vraag 12 Verslag

An electric kettle, connected to a 240V mains, produces 6.0 x 105J of heat energy to boil a quantity of water in 5 minutes. Find the resistance of the kettle.

14.4

Ω

28.8

Ω

144

Ω

288

Ω

2880

Ω

Antwoorddetails

Heat energy = Electrical energy

6 x 105 = $\frac{V^{2}}{R}$ t

R = $\frac{240 \times 240 \times 5 \times 60}{6 \times 105}$

= 28.8 $Ω$

Lees lesnotitie op Current Electricity (JAMB)

Lees lesnotitie op Heat Energy (WAEC)

Current Electricity

Heat Energy

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Vraag 14 Verslag

Which of the following features is NOT a characteristic of natural radioactivity?

Radioactivity is a nuclear phenomenon

Radioactivity is exhibited only by elements of mass number greater than 206

The radioactivity of an element is affected by electric and magnetic fields in the surroundings

Radioactive substances emits three types of radiations, a-rays,

β

-rays and y-rays

The radioactive element is transformed into a new element

Properties Of Waves: Reflection, Refraction, Diffraction

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Vraag 15 Verslag

In order to find the depth of the sea, a ship sends out a sound wave and receives an echo after one second. If the velocity of sound in water is 1500ms-1, what is the depth of the sea?

0.75km

1.50km

2.20km

3.00km

3.75km

Antwoorddetails

Echo time = 1

\div

2 = 0.5sec

depth = velocity x time

= 1500 x 0.5

= 750m = 0.75km

Lees lesnotitie op Sound Waves (WAEC)

Sound Waves

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Vraag 19 Verslag

The areas of the effort and load pistons of a hydraulic press are 0.5m2 and 5m2 respectively. If a force F1 of 100N is applied on the effort piston, the force F2 on the load is

10N

100N

500N

1000N

5000N

Antwoorddetails

\frac{l o a d}{a r e a}

=

\frac{e f f o r t}{a r e a}

$\frac{l o a d}{5}$ = $\frac{100}{0.5}$

load = 1000N

Lees lesnotitie op Position, Distance And Displacement (WAEC)

Position, Distance And Displacement

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Vraag 22 Verslag

A simple pendulum with a period of 2.0s has its length doubled. Its new period is

1.00s

1.41s

0.3s

2.83s

4.00s

Antwoorddetails

Using

\frac{T_{1}}{T_{2}}

=

\sqrt{\frac{L_{1}}{L_{2}}}

$\frac{2}{T_{2}}$ = $\sqrt{\frac{L_{1}}{2 L_{1}}}$

T2 = 2.83sec

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Vraag 24 Verslag

A quantity of gas occupies a certain volume when the temperature is -73oC and the pressure is 1.5 atmospheres. If the pressure is increased to 4.5 atmospheres and the volume is halved at the same time, what will be the new temperature of the gas?

573oC

327oC

300oC

110oC

27oC

Antwoorddetails

\frac{P_{1} V_{1}}{T_{1}}

=

\frac{P_{2} V_{2}}{T_{2}}

V1 = 2V2

$\frac{1.5 \times 2 V_{2}}{- 73 + 273}$ = $\frac{4.5 \times V_{2}}{T_{2}}$

T2 = 300K = 27oC

Lees lesnotitie op Quantity Of Heat (JAMB)

Quantity Of Heat

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Vraag 25 Verslag

A 0.05kg bullet travelling at 500ms-1 horizontally strikes a thick vertical wall. It stops after penetrating through the wall horizontal distance of 0.25m. What is the magnitude of the average force the wall exerts on the bullet?

25N

50N

250N

500N

25 000N

Antwoorddetails

F = ma

= m $\frac{(v^{2} - u^{2})}{2 s}$

F = 0.05 $\frac{(0 - (500)^{2})}{2 \times 0.25}$

F = 25 000N

Lees lesnotitie op Current Electricity (JAMB)

Current Electricity

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Vraag 29 Verslag

A transformer has a primary coil with 500 turns and a secondary coil with 2500 turns. When the voltage input to the primary coil is 120V, the output is

6000V

600V

240V

60V

24V

Antwoorddetails

For transformers,

\frac{V_{p}}{V_{s}}

=

\frac{N_{p}}{N_{s}}

=

\frac{I_{p}}{I_{s}}

$\frac{500}{2500}$ = $\frac{120}{V_{s}}$

Vs = 600v

Lees lesnotitie op Current Electricity (JAMB)

Current Electricity

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Vraag 30 Verslag

Two liquids, P at a temperature of 20oC and Q at a temperature of 80oC have specific heat capacities of 1.0Jkg-1oC-1 and 1.5J kg-1oC-1respectively. if equal masses of P and Q are mixed in a lagged calorimeter, then the equilibrium temperature is

44oC

50oC

56oC

60oC

70oC

Antwoorddetails

Heat lost = heat gained

m x (80 - $θ$ ) x 1.5 = m x ( $θ$ - 20) x 1

$θ$ = 56oC

Lees lesnotitie op Temperature And Its Measurement (JAMB)

Temperature And Its Measurement

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Vraag 31 Verslag

In a gas experiment, the pressure of the gas is plotted against the reciprocal of the volume of the gas at a constant temperature. the unit of the slope of the resulting curve is

force

force/m

work

force/m3

energy/m3

Antwoorddetails

slope = pressure

\div

\frac{1}{v o l u m e}

= $\frac{N}{m^{3}}$ x $\frac{m^{3}}{1}$

= Nm = work

Lees lesnotitie op Gas Laws (JAMB)

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Vraag 32 Verslag

A force of 100N stretches an elastic string to a total length of 20cm. If an additional force of 100N stretches the string 5cm further, Find the natural length of the string

15cm

12cm

10cm

8cm

5cm

Antwoorddetails

Using, f1 = f2

e1 = 20 - L ; e2 = 5cm

$\frac{f_{1}}{e_{1}}$ = $\frac{f_{2}}{e_{2}}$

$\frac{100}{20 - L}$ = $\frac{100}{5}$

hence, L = 15cm

Lees lesnotitie op Elasticity (JAMB)

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Vraag 35 Verslag

A wire P has half the diameter and half the length of a wire Q of similar material. The ratio of the resistance of P to that of Q is

8 : 1

4 : 1

2 : 1

1 : 1

1 : 4

Antwoorddetails

Resistance

α

\frac{l e n g t h}{a r e a}

$\frac{R_{Q}}{R_{P}}$ = $\frac{L_{Q} A_{P}}{L_{P} A_{Q}}$

LQ = 2LP

DQ = 2DP

AP = $π$ $\frac{(2 D_{P})^{2}}{2}$

= $π$ DP

AQ = $π$ $\frac{(D_{P})^{2}}{2}$

= $\frac{1}{4}$ $π$ DP

therefore, $\frac{R_{Q}}{R_{P}}$ = $\frac{2 L_{P} \times π D_{P}}{L_{P} \times \frac{1}{4} π D_{P}}$

= 2 : 1

Lees lesnotitie op Capacitors (JAMB)

Lees lesnotitie op Current Electricity (JAMB)

Current Electricity

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Vraag 36 Verslag

A metal cube of volume 103mm3 is lowered into a measuring cylinder containing water. If the internal cross-sectional area of the cylinder is 1.5 x 102mm2, by how much does the water level rise in the cylinder?

6.67 x 100mm

8.50 x 102mm

1.15 x 103mm

2.50 x 103mm

1.50 x 105mm

Antwoorddetails

Height =

\frac{v o l u m e}{a r e a}

= Height = $\frac{10^{3}}{1.5 \times 10^{2}}$

= 6.67mm

Lees lesnotitie op Measurements And Units (JAMB)

Measurements And Units

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Vraag 42 Verslag

A block of mass 2.04kg resting on a smooth horizontal plane is acted upon simultaneously by two-forces, 10N due North and 10N due East. The magnitude of the acceleration produced by the force on the block is

0.10ms-2

7.07ms-2

10.00ms-2

14.10ms-2

20.00ms-2

Antwoorddetails

R =

\sqrt{10^{2} + 10^{2}}

R = 14.14N

R = F = ma

14.14 = 2 x a

a = 7.07ms-1

Lees lesnotitie op Scalars And Vectors (WAEC)

Lees lesnotitie op Equilibrium Of Forces (WAEC)

Scalars And Vectors

Equilibrium Of Forces

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Vraag 46 Verslag

If the distance between two stationary charged particle is doubled, the magnitude of the electro-static force between them will be

doubled

halved

a quarter of its former value

unchanged

four times the original value

Antwoorddetails

F

α

\frac{1}{d^{2}}

F x d2 = constant

F1 x (d1)2 = F2 x (d2)2

d2 = 2d1

F1 x (d1)2 = F2 x (2d1)2

F2 = $\frac{1}{4}$ F1

Lees lesnotitie op Electrostatics (JAMB)

Electrostatics

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Vraag 47 Verslag

A thin aluminum plate has a surface area of 1500m at 20oC. What will be its surface area when it is cooled to -20oC? (Take the linear expansivity of aluminum to be 2.5 x 10-5k-1).

1.503m2

1.500m2

1.498m2

1.497m2

1.490m2

Antwoorddetails

β

= A2 - A1

2 X 10-5 x 2.5 = $\frac{A_{2} \times 1.5}{1.5 \times (- 20 - 20)}$

A2 = 1.498m2

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Vraag 50 Verslag

If the fundamental frequency of a closed pipe organ on a day when the speed of sound is 340ms-1 is 170Hz, then the length of the pipe is

50cm

70cm

100cm

150cm

200cm

Antwoorddetails

λ

=

\frac{v}{f}

= $\frac{340}{170}$

= 2m ; for closed pipe

L = $\frac{1}{4}$ $λ$

= $\frac{1}{4}$ x $\frac{2}{1}$

= 0.5m

= 50cm

Lees lesnotitie op Current Electricity (JAMB)

Current Electricity

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