A body projected vertically from the earth reaches a height equal to earth's radius before returning to the earth. The power exerted by the gravitational force is greatest
at the instant just before the body hits the earth
it remains constant all through
at the instant just after the body is projected
at the instant just after the body is projected
A.
at the instant just before the body hits the earth
We know
P = F. v = Fv cos θ
so just before hitting θ is zero and both F and v are maximum
A remote sensing satellite of earth revolves in a circular orbit at a height of 0.25 x 106 m above the surface of the earth. if earth 's radius is 6.38 x 106 m and g = 9.8 ms-2 then the orbital speed of the satellite is
7.76 kms-1
8.56 kms-1
9.13 kms-1
9.13 kms-1
A.
7.76 kms-1
Given, height of a satellite
h = 0.25 x 106 m
Earth's radius, Re = 6.38 x 106m
For the satellite revolving around the earth, orbital velocity of the satellite
A boy standing at the t op of a tower of 20 m height drops a stone. Assuming g = 10 ms-2, the velocity with which it hits the ground is
20 m/s
40 m/s
5 m/s
5 m/s
A.
20 m/s
Given, g = 10 ms-2 and h = 20 m
We have
A particle of mass m is thrown upwards from the surface of the earth, with a velocity u. The mass and the radius of the earth are, respectively, M and R.G are gravitational constant and g is acceleration due to gravity on the surface of the earth. The minimum value of u so that the particle does not return back to earth is
A.
A satellite S is moving in an elliptical orbit around the earth. The mass of the satellite is very small as compared to the mass of the earth. Then,
the angular momentum of S about the centre of the earth changes in direction, but its magnitude remains constant
the total mechanical energy of S varies periodically with time
the linear momentum of S remains constant in magnitude
the linear momentum of S remains constant in magnitude
D.
the linear momentum of S remains constant in magnitude
As we know that, the force on satellite is an only gravitational force which will always be towards the centre of the earth. Thus, the acceleration is S is always directed towards the centre of the earth