JAMB UTME - Physics - 1986

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

Answer Details

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?

The vibration of an air column produces the sound in the

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?

Answer Details

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

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

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

In fig 9 the value of R is

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

Which of the following is true of sounds?

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

Answer Details

Using V2 = U2 - 2gS

V = 0ms-1 at greatest height

S = $\frac{u^2}{2g}$

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

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

Answer Details

$\frac{V_1}{T_1}$ = $\frac{V_2}{T_2}$

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

V2 = 327cm3

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

Which of the following is true of magnetism?

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

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)

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

Which of the following is a derived unit?

Answer Details

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

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

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

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

The expansion of solids can be considered a disadvantage in the

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

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

Answer Details

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

Mercury is suitable as a barometric fluid because it

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

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

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)

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

Answer Details

$\theta$p = 2$\theta$q

mq = 2mp

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

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

$\frac{C_p}{Cq}$ = $\frac{2}{2}$

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

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

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

Answer Details

F = $\frac{V}{\lambda }$

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

= 75 x 1015Hz

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

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

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

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

Answer Details

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

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

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

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

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

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?

Answer Details

Total distance = 2 x 160 = 320cm

Total time = $\frac{320}{320}$ = 1s

F = $\frac{1}{1}$ = $\frac{1}{1}$

= 1Hz

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

Answer Details

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

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

Answer Details

$\lambda$ = $\frac{v}{f}$

= $\frac{20}{10}$

= 2cm ; distance between adjacent nodes

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

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

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

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

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)

Answer Details

Volume = 2 x 4 x 3 = 24m3

mass = V x D = 24 x 103

F = mg

= 24 x 103 x 10

= 24 x 104

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