The document discusses work, energy, and power. It defines key terms like work, force, kinetic energy, potential energy, and mechanical, heat, chemical, electrical, and nuclear energy. It provides examples of calculating work done and energy for objects in motion. The document also defines the unit of power as watts and provides examples of calculating power from scenarios involving work over time. It discusses different forms of energy like heat, internal, and nuclear energy and introduces the mass-energy equivalence relation E=mc2.
2. In this chapter you will come across
following terms
Work
Force
Kinetic energy
Potential Energy
Mechanical energy
Heat energy, chemical energy, Electrical
energy , Nuclear energy
Power
6. Instruction
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7. Q1.In case of negative work the angle between
the force and displacement is
(a) 00 °
(b) 450°
(c) 900 °
(d ) 180°
10. Q2. The work done on an object does not depend
upon the
(a) displacement
(b) force applied
(c) angle between force and displacement
(d) initial velocity of the object
13. Q3. A body of mass 15 kg undergoes downward
displacement of 40 m under the effect of
gravitational force. Calculate work done (g = 10
m/s2
Acceleration a= g = 10 m/s2 , mass m = 15 kg
displacement s = 40 m
a)-6000 J
b) 6000 J
c) 600 J
d) 0 J
16. Q4. A body of mass 120 g is taken vertically
upwards to reach the height of 5m. Calculate
work done (g = 10 m/s2)
a) 6 J
b) 600 J
c) 0.6 J
d) - 6 J
27. Q7. A car is accelerated on a levelled road and
attains a velocity 4 times of its initial velocity. In
this process the potential energy of the car
(a) does not change
(b) becomes twice to that of initial
(c) becomes 4 times that of initial
(d) becomes 16 times that of initial
33. Q9. A body is falling from a height h. After it has
fallen a height h/2 , it will possess
(a) only potential energy
(b) only kinetic energy
(c) half potential and half kinetic energy
(d) more kinetic and less potential energy
36. Q10. When a body falls freely towards the earth,
then its total energy
(a) increases
(b) decreases
(c) remains constant
(d) first increases and then decreases
45. Q 13. A body of mass 10 kg performs motion
along a circle of radius 5m with speed of 10
m/s. Work done during one revolution is ......
(A)2000 J
(B)1000 J
(C)500 J
(D) zero
49. Q14. 1 kWh= ........... J
(A)36 X 106
(B)3.6 X 106
(C) 3.6 X 107
(D) 3.6 X l05
50.
51.
52. Q 15.A boy of mass 40 kg climbs a staircase of
30 steps, each of 0.2m height, in 30 s. Calculate
power (g = 9.8 m/s2)
a. 8 W
b. 80 W
c. 18 W
d. 9 W
53.
54.
55. Q 16. Engine of a car of mass 1500 kg, keeps car
moving with constant velocity 5m/s. If
frictional force is 1000 N, power of engine is
...............
(A)5 kW
(B) 7.5 kW
(C)15 kW
(D) 75 kW
56.
57.
58. Q 17.Height of water dam in hydroelectric power
station is 20 m. How much water, in 1 second,
should fall on turbine, so that 1MW power is
generated ? (g = 10m/s2)
(A)5000 kg
(B)10,000 kg
(C)500 kg
(D)7,500 kg
62. Q 18.The law of conservation of energy is a
statement that
A) energy must be conserved and you are
breaking a law if you waste energy.
B) the supply of energy is limited so we must
conserve.
C) the total amount of energy is constant.
D) energy cannot be used faster than it is
created.
63.
64.
65. Q 19. The kinetic energy associated with the
random motion of the constituent particles of a
body, is known as
a) Heat Energy
b) Internal Energy
c) Nuclear Energy
d) None of the above
66.
67.
68. Q 20.Mass and energy are mutually
convertible according to the following relation
a) M= EC2
b) E = mc2
c) E = 1/2mc2
d) None of the above
