1. Number of ergs contained in one joule is ________.
A. 103
B. 105
C. 107
D. 109
ANSWER:C
SOLUTION :Therefore, 1 Joule = 10 7 erg .
2. Kinetic and potential energies of a body are the components of it’s __________ energy .
A. Chemical
B. Electrical
C. Mechanical
D. Heat
ANSWER:C
SOLUTION:The kinetic and potential energies of a body are the components of its mechanical energy.
3. Number of joule contained in 1 KW- hr is ________.
A. 9.8
B. 3.6 X 106
C. 1000
D. 105
ANSWER:B
SOLUTION:One kilowatt-hour (kWh) is equal to 3.6 million joules (3.6 × 10^6 joules). This is because one kilowatt (kW) is equal to 1,000 watts, one watt is equal to one joule per second, and one hour is equal to 3,600 seconds.
4. The time rate at which work is done or energy is transferred is called _____.
A. Power
B. Kinetic energy
C. Work
D. None of these
ANSWER:A
SOLUTION: The time rate at which work is done or energy is transferred is called power. The SI unit for power is the watt (W), where 1 watt equals 1 joule/second (1 W=1 J/s).
5. A block of mass 50 kg just slides over a horizontal distance of 1m. If Coefficient of friction between their surface is 0.2,the work done against friction is _________.
A. 98 J
B. 72 J
C. 56 J
D. 34 J
ANSWER:A
SOLUTION:A block of mass 50kg slides over a horizontal distance of 1m. If the coefficient of friction between their surfaces is 0.2,then work done against friction is: 98J.
6. Work is said to be positive on the body when the angle between force and displacement is ___________.
A. 0
B. Less than 900
C. Greater than 1800
D. None of these
ANSWER:B
SOLUTION :if angle between force apparent object is less than 90 degree then the work is positive… it is greater than 90 it is negative and if it is 90 and work done is zero.
7. A position dependent force F = 7-2X + 3x2 N acts on a small body of mass 2kg and displaces it from x = 0 to x = 5m. The work done in joules is ____.
A. 35
B. 135
C. 70
D. 270
ANSWER:B
SOLUTION:Hence, the work done is 135 J.
8. It is easier to draw up a wooden block along an inclined plane than to haul it vertically principally because ________.
A. ‘ g’ become smaller
B. The friction is reduced
C. Only a part of the weight has to be over come
D. The mass become smaller
ANSWER:C
SOLUTION: The vertical plane
W
=
m
g
h
for inclined plane
W
′
=
m
g
h
s
i
n
(
Q
)
s
i
n
Q
<
1
W
>
W
′
hence only one part of weight is to overcome
9. A spring of force constant 800 N/m has an extension of 5 cm. The work done in extending it from 5 cm to 15 cm is :
A. 24 J
B. 16 J
C. 8 J
D. 32J
ANSWER:C
SOLUTION: 8J
10. When two equal masses undergo a glancing elastic collision with one of them at rest, after the collision, they will move at ________ to each other.
A. Straight line
B. Right angles
C. Opposite
D. None of these
ANSWER:B
SOLUTION: When two spheres of equal masses undergo a glancing elastic collision with one of them at rest, after the collision they will move at right angle to each other.