In the figure, the position-time graph of a particle of mass 0.1 kg is shown. The impulse at t = 2 sec is
0.2 kg m sec-1
- 0.2 kg m sec-1
0.1 kg m sec-1
- 0.4 kg m sec-1
The pressure exerted by an electromagnetic wave of intensity I ( watt/m2 ) on a nonreflecting surface is [ c is the velocity of light ]
Ic
Ic2
I/c
I/c2
C.
I/c
Pressure = Force / area
Intensity is the quantity of energy the wave conveys per unit time across a surface of unit area and it is also equivalent to the energy density multiplied by the wave speed.
Intensity =
=
=
= P
A block of mass 10 kg is moving in x-direction with a constant speed of 10 m/sec. It is subjected to a retarding force F = -0.1 x joule/meter during its travel from x = 20 meter to x = 30 meter. Its final kinetic energy will be
475 joule
450 joule
275 joule
250 joule
The condition for a uniform spherical mass m of radius r to be a black hole is [ G = gravitational constant and g = acceleration due to gravity ]
When a ball is thrown up vertically with velocity vo, it reaches a maximum height of h. If one wishes triple the maximum height then the ball should be thrown with velocity
vo
3vo
9vo
3/2 vo
A solid sphere is rolling on a frictionless surface, show in figure with a translational velocity v m/s. If it is to climb the inclined surface then v should be
≥
≥
2gh
10/7 gh
A horizontal platform is rotating with uniform angular velocity around the vertical axis passing through its centre. At some instant of time a viscous fluid of mass 'm' is dropped at the centre and is allowed to spread out and finally fall. The angular velocity during this period
decreases continuously
decreases initially and increases again
remains unaltered
increases continuously
A ladder is leaned against a smooth wall and it is allowed to slip on a frictionless floor. Which figure represents trace of its centre of mass.
A person is standing in an elevator. In which situation he finds his weight less?
When the elevator moves upward with constant acceleration
When the elevator moves downward with constant acceleration
When the elevator moves upward with uniform velocity
When the elevator moves downward with uniform velocity