2015 - WAEC Physics Past Questions and Answers - page 2
11
Two strings each inclined at an angle 30o to the horizontal are used to hold a bucket of water weighing 20N. Calculate the tension i n each string.
A
20\(sqrt{3}\)N
B
20N
C
10\(sqrt{3}\)N
D
10N
correct option: c
Users' Answers & Comments12
A bullet fired vertically upwards reaches a height of 500m. Neglecting air resistance, calculate the magnitude of the initial velocity of the bullet. [g = 10ms-2]
A
500.0ms-1
B
100.0ms-1
C
70.0ms-1
D
50.0ms-1
correct option: b
V2 = U2 + 2gs
V2 = 0
V2 = 2gs
h = 500m
g = 10ms-2
V2 2 x 10 x 500
V2 = 10,000
V = (\sqrt{10000})
V = 100ms-1
13
A uniform bar AB is balanced on a knife-edge which is 60cm from B by a mass of 22g which hangs at C 10cm from A. Calculate the mass of the bar.
A
133.2g
B
66.0g
C
60.0g
D
22.0g
correct option: b
clockwise movement = anticlockwise movement
w x 10 = 22 x 30
w = (\frac{22 \times 30}{10})
w = 66.0g
14
A body of mass 1000kg is released from a height of 10m above the ground. Determine its kinetic energy just before it strikes the ground .[g = 10ms-2]
A
10J
B
103J
C
104J
D
105J
correct option: d
Ke = mgh
Ke = Pe
(\frac{1}{2})MV2 = mgh
Ke = 1000 x 10 x 10
Ke = 100000J
Ke = 105J
15
The crackling noise produced by aluminum roofing sheets on a house during a hot sunny day is a result of
A
thermal equilibrium of the sheets
B
conduction of heat by the sheets
C
contraction of the sheets
D
expansion of the sheets
correct option: d
Users' Answers & Comments16
Water is unsuitable for use as a thermometric liquid because it
A
expands unevenly between 0oC and 40oC
B
has narrow temperature range
C
has a concave meniscus
D
msintsin s fixed density
correct option: a
Users' Answers & Comments17
The diagram above illustrates a block ans tackle pulley system in which an effort E supports a load of 100.0N. If the efficiency of the machine is 75%, calculate the value of E
A
22.2N
B
38.0N
C
67.0N
D
75.0N
correct option: a
Given; VR = 6, e = 75%, MA = ?
e = (\frac{\text{MA}}{\text{VR}} \times \frac{100}{1})
MA =(\frac{75 \times 6}{10})
MA = (\frac{9}{2})
MA = (\frac{L}{E} = \frac{100}{E})
(\frac{9}{2} = \frac{100}{E})
9E = 100
E = (\frac{200}{9})
= 22.2N
18
A quantity of hot water at 100oC is added to 400g of water at 10oC until the temperature of the mixture is 60oC.
Calculate the mass of the hot water added. [Specific heat capacity of water =4200JKg-1 K-1]
Calculate the mass of the hot water added. [Specific heat capacity of water =4200JKg-1 K-1]
A
200g
B
320g
C
400g
D
500g
correct option: d
Heat lost by hot water = Heat gained by cold water
M x 4200 x (100 - 60 = 0.4 x 4200 x (60 - 10)
4200m x 40 = 0.4 x 4200 x 50
40m = 0.4 x 50
m = (\frac{0.4 \times 50}{40}) = 0.5kg
= 500g
19
A battery of emf 24V is connected to three resistor P, Q and R as illustrated in the diagram. Determine the voltage across the resistor Q
A
5v
B
10v
C
14v
D
24v
20
In an experiment in which a molten substance is allowed to cool, the cooling curve above was obtained. The temperature 60oC is known as the
A
vaporization point
B
cooling temperature
C
boiling point
D
melting point
correct option: d
Users' Answers & Comments