If a solid sphere of mass 1 kg and radius 0.1 m rolls without slipping at a uniform velocity of I m/s along a straight line on a horizontal floor, the kinetic energy is
J
J
J
1 J
In the diagram shown below all three rods are of equal length Land equal mass M. The system is rotated such that rod B is the axis. What is the moment of inertia of the system?
ML2
The direction of the angular velocity vector is along
the tangent to the circular path
the inward radius
the outward radius
the axis of rotation
A man of mass 60 kg records his wt on a weighing machine placed inside a lift. The ratio of wts. of man recorded when lift is ascending up with a uniform speed of 2 m/s to when it is descending down with a uniform speed of 4 m/s will be
0.5
1
2
none of these
Assertion: An astronaut experience weightlessness in a space satellite.
Reason: When a body falls freely it does not experience gravity.
If both assertion and reason are true and reason s the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
B.
If both assertion and reason are true but reason is not the correct explanation of assertion
Both the statements of assertion and the reason are correct. They are independent statements. The statement given in the reason is not the reason for the weightlessness of the astronaut. The centripetal and centrifugal forces cancel out. In the case of free fall, the pseudo acceleration, ' g ' acts upwards. The -body does not feel it. But all the same it will fall down to the earth. His mind which feels, is riding the lift of his body. The body is falling down with acceleration g. In the first case, the force of acceleration due to gravity is cancelled by the centrifugal force acting outwards. Both the statements are correct but the reason given is not the reason for the assertion.
If the temperature of a black body increases from 7°C to 287°C then the rate of energy radiation increases by
16
4
2