JAMB UTME - Physics - 1986

A man clapping his hands at regular intervals observes that the echo of a clap coincides with the next clap. If the reflecting cliff is 160m away and the speed of sound is 320ms-1, what is the frequency of the clapping?

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Total distance = 2 x 160 = 320cm

Total time = $\frac{320}{320}$ = 1s

F = $\frac{1}{1}$ = $\frac{1}{1}$

= 1Hz

Which of the following is NOT a part of a d.c. electric motor?

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A dentist obtains a linear magnification of 4 of a hole in a tooth by placing a concave mirror at a distance, of 2.0cm from the tooth. The radius of Curvature of the mirror is

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v = 4u, if u = 2cm, v = 8cm

F = $\frac{uv}{u+v}$

= $\frac{2\times 8}{2+8}$

= 1.6cm

r = 2F

= 2 x 1.6

= 3.2cm

Which of the following represents the correct precision if the length of a piece of wire is measured with a meter rule?

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A gas occupies a volume of 300cm3at a temperature of 27oC. What is its volume at 54oC, when the pressure is constant?

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$\frac{V_1}{T_1}$ = $\frac{V_2}{T_2}$

$\frac{300}{27+273}$ = $\frac{V_2}{54+273}$

V2 = 327cm3

When two objects P and Q are supplied with the same quantity of heat, the temperature change in P is observed to be twice that of Q. The ratio of the specific heat capacity of P to Q is

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$\theta$p = 2$\theta$q

mq = 2mp

Cp X mp X $\theta$p = Cq x mq x $\theta$q

$\frac{C_p{m}_q\theta q}{C_q{m}_p\theta q}$ = $\frac{\theta q\times 2mp}{2\theta qmp}$

$\frac{C_p}{Cq}$ = $\frac{2}{2}$

A pencil is placed vertically between a concave mirror and its focal point. The image of the pencil in the mirror will be

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A uniform meter rule QR is balanced on a knife edge which is 55cm from R, when a mass of 10g is hung at P as shown above, the mass of the meter rule is (Note that QP is 10cm)

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Which of the following assumptions is made in a simple pendulum experiment? the

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Which of the following is true of magnetism?

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In an experiment in which molten naphthalene is allowed to cool, the cooling curve in fig 5 was obtained, the temperature ${80}^{\circ }C$ is known as

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In which of the following arrangements is the wavelength in an increasing order?

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A constant force of magnitude F acts on an object of mass 0.04kg initially at rest at a point O. if the speed of the object when it has moved 50m from O is 500ms-1, what is the value of F?

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F = ma and V2 = U2 + 2aX

F = m$\frac{(V^2-U^2)}{2X}$

= 0.04$\frac{({500}^2-0^2)}{2\times 50}$

F = 100N

Which of the following is most strongly deflected by magnetic field?

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In fig 6, a ray of light in air strikes a glass plate at an angle of incidence 60 degrees, the reflected ray is observed to be perpendicular to the refracted ray, what is the refractive index of the glass

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A ball is thrown vertically into the air with an initial velocity u. What is the greatest height reached?

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Using V2 = U2 - 2gS

V = 0ms-1 at greatest height

S = $\frac{u^2}{2g}$

A 1000kg elevator is descending vertically with an acceleration of 1.0ms-2, if the acceleration due to gravity is 10ms-2, the tension in the suspending cable is

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The elevator is descending so the weight acts in line with the acceleration which is downwards. So according to Newton's law,
mg(weight) -R (tension/reaction) = ma

Which of the following is in a neutral equilibrium?

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Mercury is suitable as a barometric fluid because it

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Which of the following is common to evaporation and boiling? They

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Fig 4 represents a block-and-tackle pulley system on which an effort of W newtons supports a load of 120.0N if the efficiency of the system is 40% then the value of W is

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The expansion of solids can be considered a disadvantage in the

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In fig 3, three forces F1, F2, and F3 acting at O are in equilibrium. If the magnitude of F1 is 10N,and the magnitude of F2 is 5N, find the magnitude of F3

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Two objects, one having three times the mass of the other, are dropped at the same time from a tall building. When they are above the ground, the two objects will have the same

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When a box of mass 45kg, is given an initial speed of 5ms-1 it slides along a horizontal floor a distance of 3m before coming to a rest. what is the coefficient of kinetic friction between the box and the floor? (G = 10ms-2)

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The sign of the change on a charged glass rod may be determined with

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If the fig above E is an accumulator with negligible internal resistance. and the EMF 9.0V, The the total current is

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Which of the following is true of the loudness of sound? It

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What is the effect of the increase in the size of the hole of a pin-hole camera on the image? it

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If the inclination at Ibadan is 7oS, this means that

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A wave of frequency 10Hz forms a stationary wave pattern in a medium where the velocity is 20cms-1. The distance between adjacent nodes is

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$\lambda$ = $\frac{v}{f}$

= $\frac{20}{10}$

= 2cm ; distance between adjacent nodes

The mode of heat transfer which does not require a material medium is

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Which of the following properties makes metals ideal for cooking utensils?

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The specific latent heat of fusion of lead is the amount of heat required to

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Which of the following is true of sounds?

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If the refractive index of glass is 1.5, what is the critical angle at the air-glass interface?

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sin ic $\frac{1}{n}$ = $\frac{1}{1?5}$

i = sin-1$\frac{1}{1?5}$

= sin-1$\frac{10}{15}$

= sin-1$\frac{2}{3}$

A lens of focal length 12.0cm forms an upright image three times the size of a real object. The distance between the object and the images is

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F = 12cm, V = 3u

F = $\frac{uv}{u+v}$

12 = $\frac{u\times 3u}{u+3v}$

u = 16cm, and v = 48cm

therefore, distance between u and v

v = 48 - 16 = 32cm

Which of the following is a derived unit?

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Force is a derived quantity, it's unit is a derived unit

A heavy object is suspended from a string and lowered into water so that it is completely submerged. The object appears lighter because

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Which of the following is stored by a dry Leclanche cell?

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Fig 1 is a graph of force against extension for a spiral spring, the force constant of the spring is given by the

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In fig 9 the value of R is

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A rectangular tank contains water to a depth of 2m, if the base is 4m x 3m, calculate the force on the base (Density of water = 103kgm-3, g = 10ms-2)

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Volume = 2 x 4 x 3 = 24m3

mass = V x D = 24 x 103

F = mg

= 24 x 103 x 10

= 24 x 104

The vibration of an air column produces the sound in the

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The angle between the magnetic meridian and the geographic meridian at a locality on the earth is the

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The wavelength of ultraviolet radiation is 400nm. If the speed of light in air is 3 x 108ms-1, then the frequency of the ultraviolet radiation is

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F = $\frac{V}{\lambda }$

= $\frac{3\times {10}^8}{400\times {10}^9}$

= 75 x 1015Hz