WAEC - Physics (2008)

1
If the air inside a rigid box is heated, the i, average speed of the molecules increases ii. pressure of the air increases iii. average separation of the molecule increases. Which of the statements above are correct?
Відповідь
(A)
i and ii only
2
Which of the following sets of quantities is fundamental?
Відповідь
(A)
length, mass and time
3
which of the following statements about Archimedes' principle is correct? The upthrust on a body is a measure of the
Відповідь
(D)
weight of the fluid displaced
4
Which of the following is/are in random motion? i. Pollen grains in water ii. The molecules of hydrogen gas ii. Fine chalk particles floating in air
Відповідь
(D)
i, ii and iii
5
A car travelling with a uniform velocity of 30ms^-1 along a horizontal road overcomes a constant frictional force of 600N. Calculate the power of the engine of the car
Відповідь
(A)
18kW
6
A rectangular block of dimensions 2.0m x 1.0m x 0.5m weighs 200N. calculate the maximum pressure exerted by the block on a horizontal floor.
Відповідь
(D)
400Nm^-2
7
A very sensitive spring balance was used to determine the weight of an object at the north pole. When the same spring balance was used to measure the weight of the same object at the equator, it was found to reduce. The explanation for this observation is that
Відповідь
(C)
the acceleration of free fall due to gravity varies with location
8
The diagram above illustrates a Hare's apparatus. \(\mathit{e}_1, \mathit{e}_2\) represent densities and \(\mathit{h}_1, \mathit{h}_2\) heights of columns of liquids. Which of the following equations is correct?
Відповідь
(B)
\(\mathit{h}_1 = \frac{\mathit{h}_2 \mathit{e}_2}{\mathit{e}_1}\)
9
The diagram above represents the displacement-time graph of the motion of an object thrown upwards. The velocity of the object at the point P is
Відповідь
(C)
zero
10
The diagram above illustrates a bar magnet near a coil connected to a galvanometer, When the magnet is rapidly moves towards the coil i. e.m.f. is induced in the coil ii. the galvanometer needle deflects iii. the magnet is attracted by the coil. Which of the statements above is/are correct?
Відповідь
(A)
i only
11
The mass attached to a string is moving in a circular path. If the speed is doubled, the tension in the string will be
Відповідь
(C)
four times as great
12
An object of mass 2kg moving with a velocity 3ms^-11 collides head-on with another object of mass 1kg moving in the opposite direction with a velocity of 4ms^-1. If the objects stick together after collision, calculate their common speed.
Відповідь
(B)
0.67ms^-1
13
A ball is dropped and it hits the floor at a point A. It rebounds upward to a point B. While moving from A to B its?
Відповідь
(B)
potential energy is increasing
14
Which of the following devices convert heat energy to electrical energy?
Відповідь
(C)
thermocouple
15
An object of mass 0.25kg moves at a height h above the ground with a speed of 4ms-1, if its mechanical energy at this height is 12 J, determine the value of h. [g = 10ms-1]
Відповідь
(B)
4.0m
16
Which of the following equations for the efficiency of a machine is correct?
Відповідь
(D)
Efficiency = \(\frac{\text{Mechanical Advantage}}{\text{Velocity Ratio}}\) x 100%
17
The design of the thermostat of an electric iron is based on the
Відповідь
(B)
increase in size of metals when heated
18
A metal rod of length 50cm is heated from 40^oC to 80^oC. If the linear expansivity of the material is \(\alpha\), calculate the increase in length of the rod (in metres) in terms of \(\alpha\)
Відповідь
(A)
20\(\alpha\)
19
The cubic expansivity of a certain gas at constant pressure is \(\frac{1}{273} k^{-1}\). If a given mass of the gas is held at constant pressure and its volume at 0^oC is 273m³, determine the volume of the gas at 273^oC.
Відповідь
(B)
546m³
20
Water of mass 1.5kg is heated from from 30^oC to 80^oC using an electric kettle which is rated 5A, 230V. Calculate the time taken to reach the final destination [specific heat capacity of water 4200Jkg^-1K^-1]
Відповідь
(A)
4.57 minutes
21
The working principle of a pressure cooker is based on the
Відповідь
(C)
increase in the pressure of the pot
22
It takes a shorter time for a liquid to boil at the top of a mountain than at the base because at the top, the
Відповідь
(B)
pressure is lower
23
Light is considered as a transverse wave because it travels
Відповідь
(D)
in a direction perpendicular to the plane containing the electric and magnetic fields
24
In the day time, it is possible to see under shady areas such as under a tree because light has undergone
Відповідь
(D)
diffuse reflection
25
The distance between a concave mirror and an object placed in front of it is 1.0m. If the raduis of curvature of the mirror is 4.0m, the image formed will be
Відповідь
(B)
2.00m in front of the mirror
26
The image of an object formed by a convex mirror is
Відповідь
(C)
virtual, erect and diminished
27
When viewed straight down, a fish in a pond is
Відповідь
(B)
nearer than it appears to be
28
A converging lens and a screen are placed 20 cm and 80 cm respectively from an object in a straight line so that a sharp image of the object is formed on the screen. If the object is 3cm high. Calculate the height of the image formed
Відповідь
(B)
9cm
29
Which of the following defects of vision is as a result of the eye ball being too long?
Відповідь
(C)
short sight
30
a sound wave is produced fron a source ans an echo is heard t seconds afterwards. If d is the distance of the reflecting surface from the source, v the speed, p the wavelength and T the period of the wave, then
Відповідь
(B)
d = \(\frac{\lambda t}{2T}\)
31
A negatively charged rod is held close to an uncharged metal ball on an insulating stand. The ball will
Відповідь
(D)
have an excess positively charges on the side nearest the rod
32
Two bodies each carrying a charge of 2.00 x 10-10C are 5cm apart. Calculate the magnitude of the force between the charges.[\(\frac{1}{4\pi \mathit{E}_o} = 9.00 \times 10^9 Nm^2C{-2}\)]
Відповідь
(A)
1.44 x 10^-7N
33
If the charge on an object is measured as 4.0 x 10^-18C, how many excess electrons does the object possess, given that the charge of an electron is 1.6 x 10^-18C
Відповідь
(C)
25
34
Which of the following is a unit of the time rate of flow of electric charges?
Відповідь
(B)
ampere
35
A wire 1.0m long and with cross-sectional area 2.0 x 10^-7 m² has a resistance of 0.1\(\Omega\). Calculate the electrical conductivity of the wire
Відповідь
(B)
5.0 x 10⁷\(\Omega^{-1} m^{-1}\)
36
Three capacitors each of capacitance 1.5\(\mu F\) are connected in series. The total capacitance in the circuit is
Відповідь
(D)
0.5 \(\mu F\)
37
A voltmeter is a device that
Відповідь
(C)
has a very high resistance
38
Which of the following actions will not increase the sensitivity of a moving coil galvanometer?
Відповідь
(D)
using a light pointer
39
Fleming's right hand rule is also called the
Відповідь
(B)
dynamo rule
40
A transformer is required to supply 12 V_rms to operate a toy train set from a 240 V_rms. If the number of turns in the in the secondary coil is 100, calculate the number of turns required in the primary coil
Відповідь
(A)
5
41
A direct current of 5A flow through a 0.2H inductor. Calculate the energy stored in the inductor
Відповідь
(C)
2.5J
42
Both \(\gamma\)-rays and X-rays i. can be produced by thermionic emission ii. have low frequencies iii. have short wavelengths. Which of the statements above is/are correct?
Відповідь
(C)
iii only
43
When a radioactive substance undergoes a beta decay, its
Відповідь
(D)
atomic number increases by 1
44
Nuclear fission is preffered to nuclear fusion in the generation of energy because
Відповідь
(A)
very high temperature are required for fusion
45
Control in nuclear reactors is effected with boron rods because rhe rods have the ability to
Відповідь
(B)
absorb neutron