Galileo was punished by the Church for teaching that the sum is stationary and the earth moves around it. His opponents held the view that the earth is stationary and the sun moves around it. If the absolute motion has no meaing,are the two view points not equally correct or equally wrong?

Write the answer of the following question in one word- (a) What is the orbital speed of Geo-stationary satellite ? (b) For a satellite moving in an orbit around the earth what is the ratio of kinetic energy to potential energy ?

An artificial satellite is moving in a circular orbit around the earth with a speed of equal to half the magnitude of escape velocity from earth. (i). Determine the height of the satellite above the earth's surface (ii). If the satellite is stopped suddenly in its orbit and allowed to fall freely on the earth. Find the speed with it hits and surface of earth. Given M="mass of earth & R "="Radius of earth"

Consider two satellites A and B of equal mass m, moving in the same circular orbit of radius r around the earth E but in opposite sense of rotation and therefore on a collision course (see figure) (i). In terms of G,M_(e) m and r find the total mechanical energy E_(A)+E_(B) of the two satellite plus earth system before collision (ii). If the collision is completely inelastic so that wreckage remains as one piece of tangled material (mass=2m) find the total mechanical energy immediately after collision. (iii). Describe the subsequent motion of the wreckage.

A trinary star system which is a system of three orbiting around centre of mass of system has time peroid of 3 years, while the distance between any two stars of the system is 2 astronomical unit. All the three stars are identical and mass of the sun is M and total mass of this multiple star system is (a)/(b)xxM . Then find (b)/(3) ? (a and b are lowest possible integers (I astronomical unit is equal to distance between sun and earth, time period of rotation of earth around sun is 1year)

On a long horizontally moving belt (From figure) a child runs to and fro with a speed 9 kmh^(-1) (with respect to the belt) between his father and mother located 50 m apart on the moving belt. The belt moves with a speed of 4 kmh-l. For an observer on a stationary platform outside, what is the (a) Speed of the child running in the direction of motion of the belt ? (b) Speed of the child running opposite to the direction of motion of the belt ? (c) Time taken by the child in (a) and (b) ? Which of the answers alter if motion is viewed by one of the parents ?

The principle of 'parallax' in section 2.3.1 is used in the determination of distances of very distant starts. The baseline AB is the line joining the Earth's two locations six months apart in its orbit around the Sun. That is, the baseline is about the diameter of the Earth's orbit = 3xx10^(11)m . However, even the nearest stars are so distant that with such a long baseline, they show parallax only of the order of 1" (second) of arc or so. A parsec is a conventent unit of length on the astronomical scale. It is the distance of an object that will show a parallax of 1" (second of arc) from opposite ends of a baseline equal to the distance from the Earth to the Sun. How much is a parsec in terms of metres ?

When a particle is undergoing motion, the diplacement of the particle has a magnitude that is equal to or smaller than the total distance travelled by the particle. In many cases the displacement of the particle may actually be zero, while the distance travelled by it is non-zero. Both these quantities, however depend on the frame of reference in which motion of the particle is being observed. Consider a particle which is projected in the earth's gravitational field, close to its surface, with a speed of 100sqrt(2) m//s , at an angle of 45^(@) with the horizontal in the eastward direction. Ignore air resistance and assume that the acceleration due to gravity is 10 m//s^(2) . " A third observer (C) close to the surface of the reports that particle is initially travelling at a speed of 100sqrt(2) m//s making on angle of 45^(@) with the horizontal, but its horizontal motion is northward". The third observer is moving in :-

An artificial satellite is moving in a circular orbit around the earth with a speed of equal to half the magnitude of escape velocity from earth. If the satellite is stopped suddenly in its orbit and allowed to fall freely on the earth. Find the speed with which it hits the surface of earth. Given, M=mass of earth & R =Radius of earth

The planet Mars has two moons, phobos and delmos. (i) phobos has a period 7 hours, 39 minutes and an orbital radius of 9.4 xx 103 km. Calculate the mass of mars. (ii) Assume that earth and mars move in circular orbits around the sun, with the martian orbit being 1.52 times the orbital radius of the earth. What is the length of the martian year in days ?

Mean solar day is the time interval between two successive noon when sun passes through zenith point (meridian). Sidereal day is the time interval between two successive transit of a distant star through the zenith point (meridian). By drawing appropriate diagram showing the earth's spin and orbital motion, show that mean solar day is 4 min longer than the sidereal day. In other words, distant stars would rise 4 min early every successive day. As per diagram, the earth moves from the point P to Q in one solar day.