WBJEE Entrance Question
Ques-
A drum of radius R and mass M, rolls down without slipping along an inclined plane of angleθ . The frictional force:
a) Dissipates energy as heat
b) Decreases the rotational motion
c) Converts translational energy to rotational energy
d) Decreases the rotational and translational motion
Ques-
A coin of mass 4.8 kg and radius one metre is rolling on a horizontal surface without sliding with angular velocity 600 rotations/min. What is total kinetic energy of the coin?
a) 360 J
b) 1440π J
c) 600π2 J
d) 4000π2 J
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The motion of planets in the solar system is an example of the conservation of
a) Energy
b) Angular momentum
c) Mass
d) Linear momentum
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A body is projected from the ground with some angle to the horizontal. What happens to the angular momentum about the initial position in this motion?
a) Remains same
b) First increases and then decreases
c) Increases
d) Decreases
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The total number of contributing structures showing hyperconjugation (involving C — H bonds) for the following carbocation is :
a) 3
b) 6
c) 5
d) 4
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The decreasing order of stability of following anions is –
a) R > Q > P > S
b) S > P > R > Q
c) Q > R > S > P
d) P > Q > R > S
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Among the cyclic ions:
the aromatic character is shown by:
a) P, Q, R and S
b) Q and S
c) Q and R
d) P and S
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A tertiary butyl carbocation is more stable than a secondary butyl carbocation because of which of the following?
a) – I effect of – CH groups
b) +R effect of – CH groups
c) – R effect of – CH groups
d) Hyperconjugation
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Which one of the following is the strongest acid?
a) 
b) 
c) 
d) 
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By what percentage will the transmission range of a TV tower be affected when the height of the tower is
increased by 21% ?
(1) 12%
(2) 15%
(3) 14%
(4) 10%
Ques-
The number of air molecules per cm3 increased from 3 × 1019 to 12 × 1019. The ratio of collision frequency of air molecules before and after the increase in the number respectively is :
(1) 0.25
(2) 0.75
(3) 1.25
(4) 0.50