2014 - JAMB Physics Past Questions and Answers - page 2
11
The energy in the nucleus of atoms produce heat which can be used to generate
A
Kinetic energy
B
Mechanical energy
C
Electrical energy
D
Potential energy
correct option: a
Users' Answers & Comments12
A machine whose efficiency is 75% is used to lift a load of 1000N. Calculate the effort put in to the machine if it has a Velocity ratio of 4.
A
343.32N
B
233.33N
C
333.33N
D
334.33N
correct option: c
\(\frac{MA}{VR}\times\frac{100}{1}=efficiency\)
\(\frac{L}{E}\frac{1}{VR}\times\frac{100}{1}=75\)
\(\frac{1000}{E}\frac{1}{4}\times\frac{100}{1}=75\)
\(E = \frac{250 \times 100}{75}\)
E = 333.3N
Users' Answers & Comments\(\frac{L}{E}\frac{1}{VR}\times\frac{100}{1}=75\)
\(\frac{1000}{E}\frac{1}{4}\times\frac{100}{1}=75\)
\(E = \frac{250 \times 100}{75}\)
E = 333.3N
13
A wheel and an axle is used to raise a load whose weight is 800N when an effort of 250N is applied. If the radii of the wheel and axle are 800mm and 200mm respectively, the efficiency of the machine is
A
90%
B
80%
C
85%
D
87%
correct option: b
VR = 800/200 = 4
\(Efficiency = \frac{MA}{VR} \times \frac{100}{1}\)
\(Efficiency = \frac{L}{E} \times \frac{1}{VR} \times \frac{100}{1}\)
\(Efficiency = \frac{800}{250} \times \frac{1}{4} \times \frac{100}{1}\)
= 78.74%
= 80%
Users' Answers & Comments\(Efficiency = \frac{MA}{VR} \times \frac{100}{1}\)
\(Efficiency = \frac{L}{E} \times \frac{1}{VR} \times \frac{100}{1}\)
\(Efficiency = \frac{800}{250} \times \frac{1}{4} \times \frac{100}{1}\)
= 78.74%
= 80%
14
A force of 500N1 is applied to a steel wire of cross-sectional area 0.2m2, The tensile stress is
A
2.5x104Nm-2
B
1.0x102Nm-2
C
1.0x103Nm-2
D
2.5x103Nm-2
correct option: d
\(Stress = \frac{Force}{Area}\)
\(Stress = \frac{500}{0.2} = 2500\)
= 2.5 x 103Nm-3
Users' Answers & Comments\(Stress = \frac{500}{0.2} = 2500\)
= 2.5 x 103Nm-3
15
The small droplets of water that form on the grass in the early hours of the morning is
A
Fog
B
Haul
C
Mist
D
Dew
correct option: d
Users' Answers & Comments16
What is the equivalent of 20K in Celsius scale?
A
20oC
B
293oC
C
68oC
D
36oC
17
The equation PaVbTc= constant reduces to Charles Law if
A
a=1, b=1and c=0
B
a=1, b=0 and c=-1
C
a=0, b=1 and c=1
D
a=0, b=1 and c=-1
18
The quantity of heat needed to raise the temperature of a body by 1K is the body's
A
Heat capacity
B
Internal energy
C
Specific heat capacity
D
Latent heat of fusion
correct option: a
Users' Answers & Comments19
The melting point of a substance is equivalent to its
A
Vapour Pressure
B
Solidification Temperature
C
Liquidification Temperature
D
Solidification Pressures
correct option: b
Users' Answers & Comments20
The temperature at which the water vapour present in the air is just sufficient to saturate air is
A
Boiling point
B
Ice point
C
Saturation point
D
Dew point
correct option: d
Users' Answers & Comments