PART - 1 CH - 7 Gravitation Physics - PART - 1 CH - 7 Gravitation

What would be the reason for the absence of atmosphere on the Moon?

An object performs action due to force acting towards a point. The mgnitude of force is inversely proportional to the square of the distance. The path of the object will be:

What is the formula to find escape velocity?

At whose name did India launch the first statellie?

Relationship between escape velocity and orbital velocity is Ve = ...............

The value of g on the surface of the Moon is only ................ part of the value of g on earth's surface.

The value of g on the surface of planet is................ than that on the earth.

The magnitude of centripetal force is ................ distance between the planet and the sun .

Newton's law of gravity is not true for particles located distances less than ................ .

If a simple pendulum is taken to a mountain, its time period will increase.(True/False)

The value of gravitational acceleration at the center of the earth will not be zero.(True/False)

The body revolving around a planet is called satellite and the body revolving around a star is called planet.(True/False)

Which of the following symptoms is likely to afflict an astronaut in space (a) swollen feet, (b) swollen face, (c) headache, (d) orientational problem.

Choose the correct alternative :
(a) If the zero of potential energy is as infinity, the total energy of an orbiting satellite is negative of its kinetic/potential energy.
(b) The energy required to launch an orbiting satellite out of earth's gravitational influence is more/ less than the energy required to project a stationary object at the same height (as the satellite) out of earth's influence.

For the above problem, the direction of the gravitational intensity at an arbitrary point P is indicated by the arrow (i) d, (ii) e, (iii) f, (iv) g.

Mention Kepler's law.

To what height above the earth will the value of gravitational acceleration become one fourth of the value at Earth's surface?

Does the escape speed of a body from the earth depend on (a) the mass of the body, (b) the location from where it is projected, (c) the direction of projection, (d) the height of the location from where the body is launched?

Suppose there existed a planet that went around the Sun twice as fast as the earth. What would be its orbital size as compared to that of the earth?

In the following two exercises, choose the correct answer from among the given ones : The gravitational intensity at the centre of a hemispherical shell of uniform mass density has the direction indicated by the arrow.

Answer the following :
(a) You can shield a charge from electrical forces by putting it inside a hollow conductor. Can you shield a body from the gravitational influence of nearby matter by putting it inside a hollow sphere or by some other
means?
(b) An astronaut inside a small space ship orbiting around the earth cannot detect gravity. If the space station orbiting around the earth has a large size, can he hope to detect gravity?
(c) If you compare the gravitational force on the earth due to the sun to that due to the moon, you would find that the Sun’s pull is greater than the moon’s pull. (you can check this yourself using the data available in the succeeding exercises). However, the tidal effect of the moon’s pull is greater than the tidal effect of sun.Why?

A comet orbits the sun in a highly elliptical orbit. does the comet have a constant (a) linear speed, (b) angular speed, (c) angular momentum, (d) kinetic energy, (e) potential energy, (f) total energy throughout its orbit? Neglect any mass loss of the comet when it comes very close to the sun.

Two heavy spheres each of mass 100 kg and radius 0.10 m are placed 1.0m apart on a horizontal table. What is the gravitational force and potential at the mid point of the line joining the centres of the spheres? Is an object placed at that point in equilibrium? If so, is the equilibrium stable or unstable?

The escape speed of a projectile on the earth’s surface is 11.2 km s^–1. A body is projected out with thrice this speed. What is the speed of the body far away from the earth ? Ignore the presence of the sun and other planets.

Two starts each of one solar mass (= 2 × 10³⁰ kg) are approaching each other for a head on collision. When they are a distance 10⁹ km, their speeds are negligible. What is the speed with which they collide? The radius of each start is 10⁴ km. Assume the stars to remain undistorted until they collide. (Use the known value of G).