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15 questions
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
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
In case of negative work the angle between the force and displacement is
(a) 0°
(b) 45°
(c) 90°
(d ) 180°
An iron sphere of mass 10 kg has the same diameter as an aluminium sphere of mass is 3.5 kg. Both spheres are dropped simultaneously from a tower. When they are 10 m above the ground, they have the same
(a) acceleration
(b) momenta
(c) potential energy
(d) kinetic energy
A girl is carrying a school bag of 3 kg mass on her back and moves 200 m on a levelled road. The work done against the gravitational force will be (g =10 m s–2)
6×103 J
6 J
0.6 J
zero
Which one of the following is not the unit of energy?
(a) joule
(b) newton metre
(c) kilowatt
(d) kilowatt hour
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
Water stored in a dam possesses
(a) no energy
(b) electrical energy
(c) kinetic energy
(d) potential energy
A body is falling from a height h. After it has fallen a height 2h , 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
The number of joules contained in 1kWh is
36×106 J
3.6×107J
3.6×106J
3.7×107J
Two army persons A and B each of weight of 500N climb up a rope through a height of 10m.
A takes 20s while B takes 40s to achieve this task. what is ratio of the power of person A and B?
1:2
1:4
2:1
14:1
If speed of a car becomes 2 times, its kinetic energy becomes
4 times
8 times
16 times
12 times
Mechanical energy of a body includes
Kinetic energy only
Potential energy only
kinetic energy and potential energy
None of these
Commercial unit of energy is
Joule
kWh
Watt
Newton
When a coil spring is compressed, the work is done on the spring. the elastic potential energy
Increases
Decreases
Disappears
Remain unchanged
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