JAMB - Physics (2012)

1
In order to remove the error of parallax when taking measurements with a metre rule, the eye should be focused
Odpověď
(C)
vertically downwards on the markings
2
A load is pulled at a uniform speed along a horizontal floor by a rope at 45^o to floor. If the force in the rope is 1500N, what is the frictional force on the load ?
Odpověď
(D)
1061N
3
Calculate the total distance covered by a train before coming to rest if its initial speed is 30ms^-1 with a constant retardation of 0.1m^-2
Odpověď
(B)
4500m
4
A car starts from rest and moves with a uniform acceleration of 30ms^-2 for 20s. Calculate the distance covered at the end of the motion
Odpověď
(A)
6km
5
A rocket is fired from the earth's surface to a distant planet. By Newton's law of universal gravitation, the force F will
Odpověď
(A)
increase as r reduces
6
If a freely suspended object is pulled to one side and released, it oscillates about the point of suspension because the
Odpověď
(A)
acceleration is directly proportional to the displacement
7
An object moves in a circular path of radius 0.5m with a speed of 1ms^-1 What is its angular velocity?
Odpověď
(C)
2 rads^-1
8
An object of mass 20kg slides down an inclined plane at an angle of 30^o to the horizontal. The coefficient of static friction is?
[g = 10ms^-2]
Odpověď
(D)
0.6
9
A block and tackle is used to raise a load of 250N through a vertical distance of 30m. What is the efficiency of the system if the work done against friction is 1500J?
Odpověď
(C)
83.3%
10
If a load of 1 kg stretches a cord by 1.2cm, what is the force constant of the cord? {g=10ms^-2}
Odpověď
(B)
833Nm^-1
11
An object of volume 1 m ³ and mass 2kg is totally immersed in a liquid of density 1 kgm^-3 . Calculate its apparent weight.
Odpověď
(B)
10N
12
The pressure at any point in a liquid at rest depends only on the
Odpověď
(A)
depth and the density
13
A balloon whose volume is 300m³ is filled with hydrogen. If the density of air is 1.3 kgm^-3, find the upthrust on the balloon. [g = 10ms^-2]
Odpověď
(C)
3900N
14
Clinical thermometers are examples of
Odpověď
(D)
mercury- in - glass thermometer
15
Two metals P and Q are heated through the same temperature difference. If the ratio of the linear expansivities of P to Q is 2:3 and the ratio of their
length is 3: 4 respectively, the ratio of the increase in lengths of P to Q is
Odpověď
(A)
1:2
16
2000cm³ of a gas is collected at 27^oC and 700mmHg. What is the volume of the gas at standard temperature and pressure?
Odpověď
(C)
1676.3cm³
17
Calculate the temperature change when 500J of heat is supplied to 100g of water

[specific heat capacity of water = 4200JKg\(^{-1}\)k\(^{-1}\)]
Odpověď
(C)
1.2^oC
18
Which of the following is NOT a factor that can increase the rate of evaporation of water in a lake?
Odpověď
(A)
increase in the pressure of the atmosphere
19
The quantity of heat energy required to melt completely 1 kg of ice at - 30^oC is
[latent heat of fusion = 3.5 x 10 ⁵Jkg ^-1, specific heat capacity of ice = 2.1x10 ³Jkg ^-1K ^-1]
Odpověď
(B)
4.13x10 ⁵J
20
I. It is a rapid, constant and irregular motion of tiny particles. II. It gives evidence that tiny particles of matter called molecules exist. III. It takes place only in gases. IV. It gives evidence that molecules are in a constant state of random motion. which of the combinations above is correct about Brownian notion?
Odpověď
(D)
l, ll and lV only
21
The equation of a wave traveling in a horizontal direction is expressed as y = 15 sin \(\frac{2\pi}{5}\) (60t - x). What is its wavelength?
Odpověď
(C)
5m
22
Which of the following factors will affect the velocity of sound?
Odpověď
(C)
Wind travelling in the same direction of the sound
23
The characteristic of a vibration that determines its intensity is the
Odpověď
(D)
Amplitude
24
Where can a man place his face to get an enlarged image when using a concave mirror to shave?
Odpověď
(C)
Between the principal focus and the pole
25
A pinhole camera is placed 300m in front of a building so that the image is formed on a screen 5cm from the the pinhole. If the image is 2.5cm high, the height of the building will be
Odpověď
(D)
150m
26
The magnification of an object 2cm tall when placed 10cm in front of a plane mirror is
Odpověď
(B)
1.0
27
After reflection from the concave mirror, rays of light from the sun converges
Odpověď
(B)
at the focus
28
A glass block of thickness 10cm is placed on an object. If an observer views the object vertically, the displacement of the object is
Odpověď
(A)
3.33cm
29
I. Rays of light travel from a less dense medium to a denser medium. II. The Angle of incidence is greater than critical angle. III. Rays of light travel from a denser medium to a less dense medium. Which of the statements above are conditions for total internal reflection to occur?
Odpověď
(C)
II & III only
30
The use of lenses is Not applicable in the
Odpověď
(C)
periscope
31
Disperson of white light is the ability of white light to
Odpověď
(D)
separate to its component colours
32
A newly charged 12V accumulator can easily start a car whereas eight new dry cells in series with a effective e.m.f. of 12V cannot start the same car because
Odpověď
(B)
The current capacity is low
33
The fuse in an electric device is always connected to the
Odpověď
(C)
live side of an electric supply
34
A particle carrying a charge of 1. 0 x 10^-8C enters a magnetic field at 3.0x 10^-2 ms ^-1 at right angles to the field. If the force on this particle is 1.8 x 10^-8N, what is the magnitude of the field?
Odpověď
(B)
6.0x10T
35
The current output from of an a.c. source is given as I = 10 sin to t. The d.c equivalent of the current is
Odpověď
(B)
7.1A
36
A conductor of length 1m moves with a velocity of 50ms^-1 at an angle of 30^o to the direction of a uniform magnetic field of flux density 1.5Wbm^-2. What is the e.m.f induced in the conductor?
Odpověď
(A)
37.5V
37
The process of detecting a pin mistakenly swallowed by a child is X-ray
Odpověď
(A)
Diagnosis
38
Which of the following CANNOT be deflected by both electric and magnetic fields?
Odpověď
(A)
Gamma rays
39
A piece of radioactive material contains 1000 atmos. If its half -life is 20seconds, the time taken for 125 atoms to remain is
Odpověď
(D)
60 seconds
40
The p-n junction diodes can act as rectifiers because they
Odpověď
(A)
conduct current when forward-biased