Biology
Famous palaeonotologist/Palaeobotanist of India was:
BiologyGeneral
- P.Maheshwari
- B.P. Pal
- S. R. Kashyap
- B.Sahni
Answer:The correct answer is: B.Sahni
Book A Free Demo
+91 
Grade*
Select Grade
Related Questions to study
physics-
A disc is rolling (without slipping) on a horizontal surface 
is its centre and 
and 
are two points equidistant from . Let 
, 
and 
be the magnitude of velocities of pints 
and respectively, then
In case of pure rolling bottommost point is the instantaneous centre of zero velocity.
Velocity of any point on the disc,
,
where
is distance of point from 
.
Velocity of any point on the disc,
,where
is distance of point from .A disc is rolling (without slipping) on a horizontal surface is its centre and and are two points equidistant from . Let , and be the magnitude of velocities of pints and respectively, then
physics-General
In case of pure rolling bottommost point is the instantaneous centre of zero velocity.
Velocity of any point on the disc,,
where is distance of point from .
Velocity of any point on the disc,
,where
is distance of point from .physics-
A small object of uniform density roll up a curved surface with an initial velocity 
. If reaches up to a maximum height of 
with respect to the initial position. The object is
Body is disc.A small object of uniform density roll up a curved surface with an initial velocity . If reaches up to a maximum height of with respect to the initial position. The object is
physics-General
Body is disc.physics-
A uniform rod 
of length 
and mass 
is free to rotate about point 
. The rod is released from rest in the horizontal position. Given that the moment of inertia of the rod about is
, the initial angular acceleration of the rod will be
The moment of inertia of the uniform rod about an axis through one end and perpendicular to its length is
Where is mass of rod and is length.
Torque
acting on centre of gravity of rod is given by
or
or
or
Where
is mass of rod and is length.Torque
acting on centre of gravity of rod is given byor
or
or
A uniform rod of length and mass is free to rotate about point . The rod is released from rest in the horizontal position. Given that the moment of inertia of the rod about is, the initial angular acceleration of the rod will be
physics-General
The moment of inertia of the uniform rod about an axis through one end and perpendicular to its length is
Where is mass of rod and is length.
Torque acting on centre of gravity of rod is given by
or
or
or
Where
is mass of rod and is length.Torque
acting on centre of gravity of rod is given byor
or
or
maths-
If 
then descending order of 
is
If then descending order of
is
maths-General
physics-
Three rods of the same mass are placed as shown in figure. What will be the coordinates of centre of mass of the system?
As shown in figure, centre of mass of respective rods are at their respective mid points. Hence centre of mass of the system has coordinates (
,
). then
,). thenThree rods of the same mass are placed as shown in figure. What will be the coordinates of centre of mass of the system?
physics-General
As shown in figure, centre of mass of respective rods are at their respective mid points. Hence centre of mass of the system has coordinates (,). then
,). thenphysics-
Two blocks and 
are connected by a massless string (shown in figure). A force of 30 N is applied on block . The distance travelled by centre of mass in 2 s starting from rest is
The acceleration of centre of mass is
m
mTwo blocks and are connected by a massless string (shown in figure). A force of 30 N is applied on block . The distance travelled by centre of mass in 2 s starting from rest is
physics-General
The acceleration of centre of mass is
m
mphysics-
Find the velocity of centre of the system shown in the figure.
Here, 
kg, 
kg, 
kg, kg, Find the velocity of centre of the system shown in the figure.
physics-General
Here, kg,
kg,
kg, kg, physics-
The blocks and , each of mass , are connected by massless spring of natural length 
and spring constant 
. The blocks are initially resting on a smooth horizontal floor with the spring at its natural length, as shown in figure. A third identical block , also of mass , moves on the floor with a speed along the line joining and , and collides with . Then
The compression of spring is maximum when velocities of both blocks and is same. Let it be 
, then from conservation law of momentum
kinetic energy of 
system at that stage
Further loss in KE> = gain in elastic potential energy
, 
and is same. Let it be , then from conservation law of momentum kinetic energy of system at that stageFurther loss in KE> = gain in elastic potential energy
, The blocks and , each of mass , are connected by massless spring of natural length and spring constant . The blocks are initially resting on a smooth horizontal floor with the spring at its natural length, as shown in figure. A third identical block , also of mass , moves on the floor with a speed along the line joining and , and collides with . Then
physics-General
The compression of spring is maximum when velocities of both blocks and is same. Let it be , then from conservation law of momentum
kinetic energy of system at that stage
Further loss in KE> = gain in elastic potential energy
,
and is same. Let it be , then from conservation law of momentum kinetic energy of system at that stageFurther loss in KE> = gain in elastic potential energy
, physics-
A set of 
identical cubical blocks lies at rest parallel to each other along a line on a smooth horizontal surface. The separation between the near surfaces of any two adjacent blocks is . The block at one end is given a speed towards the next one at time 
. All collision are completely elastic. Then
Time taken by first block to reach second block 
Since collision is 100% elastic, now first block comes to rest and 2nd block starts moving towards the 3rd block with a velocity and takes time to reach 3rd block and so on
Total time 
time 
Finally only the lastth block is in motion velocity , hence final velocity of centre of mass
Since collision is 100% elastic, now first block comes to rest and 2nd block starts moving towards the 3rd block with a velocity
and takes time to reach 3rd block and so on Total time time Finally only the last
th block is in motion velocity , hence final velocity of centre of massA set of identical cubical blocks lies at rest parallel to each other along a line on a smooth horizontal surface. The separation between the near surfaces of any two adjacent blocks is . The block at one end is given a speed towards the next one at time . All collision are completely elastic. Then
physics-General
Time taken by first block to reach second block
Since collision is 100% elastic, now first block comes to rest and 2nd block starts moving towards the 3rd block with a velocity and takes time to reach 3rd block and so on
Total time time
Finally only the lastth block is in motion velocity , hence final velocity of centre of mass
Since collision is 100% elastic, now first block comes to rest and 2nd block starts moving towards the 3rd block with a velocity
and takes time to reach 3rd block and so on Total time time Finally only the last
th block is in motion velocity , hence final velocity of centre of masschemistry-
Which of the following noble gas was reacted with 
by Bartlett to prepare the first noble gas compounds -
Which of the following noble gas was reacted with by Bartlett to prepare the first noble gas compounds -
chemistry-General
physics-
In the given figure, two bodies of mass 
and 
are connected by massless spring of force constant and are placed on a smooth surface (shown in figure), then
The resultant force on the system is zero. So, the centre of mass of system has no acceleration
In the given figure, two bodies of mass and are connected by massless spring of force constant and are placed on a smooth surface (shown in figure), then
physics-General
The resultant force on the system is zero. So, the centre of mass of system has no acceleration
physics-
Two blocks and (
) are connected with a spring of force constant and are inclined at a angel 
with horizontal. If the system is released from rest, which one of the following statements is/are correct?
If the surface is smooth, then relative acceleration between blocks is zero. So, no compression or elongation takes place in spring. Hence, spring force on blocks is zero.
Two blocks and () are connected with a spring of force constant and are inclined at a angel with horizontal. If the system is released from rest, which one of the following statements is/are correct?
physics-General
If the surface is smooth, then relative acceleration between blocks is zero. So, no compression or elongation takes place in spring. Hence, spring force on blocks is zero.
physics-
Two negatively charges particles having charges 
and 
and masses and respectively are projected one after another into a region with equal initial velocity. The electric field 
is along the 
-axis, while the direction of projection makes an angle a with the -axis. If the ranges of the two particles along the 
-axis are equal then one can conclude that
Here, effected gravitational acceleration is
It means,
for both particles are same
This is possible when
and 
It means,
for both particles are sameThis is possible when
and Two negatively charges particles having charges and and masses and respectively are projected one after another into a region with equal initial velocity. The electric field is along the -axis, while the direction of projection makes an angle a with the -axis. If the ranges of the two particles along the -axis are equal then one can conclude that
physics-General
Here, effected gravitational acceleration is
It means, for both particles are same
This is possible when
and
It means,
for both particles are sameThis is possible when
and physics-
A particle of mass moves in the 
plane with a velocity along the straight line . If the angular momentum of the particle with respect to origin is 
when it is at and 
when it is at , then
From the definition of angular momentum,
Therefore, the magnitude of is
where
is the distance of closest approach of the particle to the origin. As 
is same for both the particles, hence 
.
Therefore, the magnitude of
iswhere
is the distance of closest approach of the particle to the origin. As is same for both the particles, hence .A particle of mass moves in the plane with a velocity along the straight line . If the angular momentum of the particle with respect to origin is when it is at and when it is at , then
physics-General
From the definition of angular momentum,
Therefore, the magnitude of is
where is the distance of closest approach of the particle to the origin. As is same for both the particles, hence .
Therefore, the magnitude of
iswhere
is the distance of closest approach of the particle to the origin. As is same for both the particles, hence .physics-
In the given figure four identical spheres of equal mass are suspended by wires of equal length 
, so that all spheres are almost touching to each other. If the sphere 1 is released from the horizontal position and all collisions are elastic, the velocity of sphere 4 just after collision is
When the sphere 1 is released from horizontal position, then from energy conservation, potential energy at height 
kinetic energy at bottom
Or
Or
Since, all collisions are elastic, so velocity of sphere 1 is transferred to sphere 2, then from 2 to 3 and finally from 3 to 4. Hence, just after collision, the sphere 4 attains a velocity equal to
kinetic energy at bottomOr
Or
Since, all collisions are elastic, so velocity of sphere 1 is transferred to sphere 2, then from 2 to 3 and finally from 3 to 4. Hence, just after collision, the sphere 4 attains a velocity equal to
In the given figure four identical spheres of equal mass are suspended by wires of equal length , so that all spheres are almost touching to each other. If the sphere 1 is released from the horizontal position and all collisions are elastic, the velocity of sphere 4 just after collision is
physics-General
When the sphere 1 is released from horizontal position, then from energy conservation, potential energy at height kinetic energy at bottom
Or
Or
Since, all collisions are elastic, so velocity of sphere 1 is transferred to sphere 2, then from 2 to 3 and finally from 3 to 4. Hence, just after collision, the sphere 4 attains a velocity equal to
kinetic energy at bottomOr
Or
Since, all collisions are elastic, so velocity of sphere 1 is transferred to sphere 2, then from 2 to 3 and finally from 3 to 4. Hence, just after collision, the sphere 4 attains a velocity equal to