Physics 2 Marks Questions

Kinetic energy.Explanation:
Total mechanical energy of a satellite is the sum of its kinetic energy (always positive) and potential energy (may be negative). At infinity, the gravitational potential energy of the satellite is zero. As the Earth-satellite system is a bound system, the total energy of the satellite is negative. Thus, the total energy of an orbiting satellite at infinity is equal to the negative of its kinetic energy.

Yes, Astronaut can hope to detect gravity if the size of th e spaceship is extremely large, then the magnitude of the gravity will become appreciable and hence the gravitational effect of the spaceship may been me measurable.

No. Electrical forces depend upon the nature of the intervening medium while the gravitational forces don’t depend upon the nature of the intervening medium. So, such shielding acts are not possible in case of gravitation i.e., gravity screens are not possible.

Earth moon distance is very small as compared to earth-sun distance. Tidal effect is inversely proportional to the cube of the distance it means it is not governed by inverse square law like the gravitational force (which obeys inverse square law). Hence, tidal effect of moon is larger than that due to the sun.

The gravitational force does not depend upon the nature of the medium, but the electric force depends on the intervening medium between the charge and the electric field. So we cannot shield a body from the gravitational force.

If the revolution period of a satellite is same as that of the earth, it is called a geo-stationary satellite. Yes, geo-synchronous satellites are geo-stationary satellites.

The weight will become zero under the following circumstances:

1. During free fall.
2. At the centre of the earth.
3. In an artificial satellite.
4. At a point where gravitational pull of earth is equal to the gravitational pull of the Moon.

If the earth stops rotating, the weight of the object increases due to absence of centrifugal force. However, the weight at the poles remains the same.

The escape velocity from the earth surface is about 11.2km/sec which is greater than the r.m.s. velocity of the air molecules. The escape velocity from the moon's surface is about 2.4km/sec which is less than the r.m.s. velocity of the air molecules. Hence, the earth has an atmosphere and the moon does not.

1. Remains dependent on the choice of origin.
2. Potential energy is independent since it depends only on separation.

The total energy of a satellite in any orbit, E = -K, where K is its KE in that orbit. If its kinetic energy is doubled, i.e. an additional kinetic energy (K) is given to it, E = -K + K = 0 and the satellite will leave its orbit and go to infinity.

1. Velocity acquired is more than the escape velocity to go out in space.
2. Provide sufficient velocity to move in a path of its own.

The first system has the outer most masses closer to each other than the second system. Hence the gravitational P.E. of the second system is lesser than that of the first system.

The earth is orbiting round the sun in a stable orbit (nearly circular) such that the gravitational attraction of the sun just provides the required centripetal force to the earth for its orbital motion. So, net force on the earth is zero and consequently, the earth does not fall into the sun.

No, generally the geo-stationary satellites will be in the equatorial plane. Since New Delhi does not lie in this plane, it is not possible.

Satellite will move tangentially with constant speed equal to its orbital velocity at the time the force ceases to act.

The orbit of the satellite is independent of its mass. The released mass will continue to orbit the earth as a satellite and hence, will not fall on the earth.

The gravitational force between satellite and the earth provides the centripetal force required by the satellite to move in a circular orbit. The satellite orbits around earth at such a higher height where air friction is neglible.

Kinetic energy.Explanation:
Total mechanical energy of a satellite is the sum of its kinetic energy (always positive) and potential energy (may be negative). At infinity, the gravitational potential energy of the satellite is zero. As the Earth-satellite system is a bound system, the total energy of the satellite is negative. Thus, the total energy of an orbiting satellite at infinity is equal to the negative of its kinetic energy.

Acceleration caused on earth due to apple is negligible due to large mass of earth and because the observer is in the same frame so he cannot see motion.

The change in gravitational potential energy of a body between two given points depends only upon the position of the given points and is independent of the path followed. is due to the fact that the gravitational force is a conservative force and work done by a conservative force depends only on the position of initial and final points and is independent of path followed.

The safety of a person depends upon the momentum with which the person hits the planet. Since, the mass of the person is constant, therefore the maximum velocity v is the limiting factor.

The food packet will not fall on the earth. As the satellite as well as astronaut were in a state of weightlessness, hence, the food packet, when dropped by mistake, will also start moving with the same velocity as that of satellite and will continue to move along with the satellite in the same orbit.

The food packet will not fall on the Earth. As the satellite as well as astronaut were in a state of weightlessness, hence the food packet, when dropped by mistake, will also start moving with the same velocity as that of satellite and will continue to move along with the satellite in the same orbit.

Gravitational force, electrostatic force due to point mass and point charges are the examples of central force. Spin dependent nuclear force, magnetic force between two current carrying loops are the examples of non - central forces.

In going from earth to moon, the spacecraft has to do more work against the greater gravitational attraction of the earth. For the return journey, moon's gravitational force is much less, hence less work is done and less fuel is consumed.

Inside a spherical shell, gravitational force is zero. Since there is no mass inside, the gravitational field and thereby the force is zero.

Astronaut inside a small spaceship experience a very small negligible constant acceleration and hence astronaut feel weight less ness. If the space station has too much large mass and size then he can only experience acceleration due to gravity in the proximity of moon or on the moon.

As the acceleration due to gravity on hills is less than that on the surface of the earth (effect of height), therefore, a tennis ball bounces higher on hills than on plains.

The astronauts and the satellite require the centripetal force to revolve around the earth. Their weight is used up in providing the necessary centripetal force. Hence an astronaut feels weightlessness in the space.

Yes, Astronaut can hope to detect gravity if the size of th e spaceship is extremely large, then the magnitude of the gravity will become appreciable and hence the gravitational effect of the spaceship may been me measurable.

Any change in the distribution of the earth's mass will not affect the variation of acceleration due to gravity with height. This is because for a point outside the earth, the whole mass of the earth is effective and the earth behaves as a homogeneous sphere.

Earth rotates on its axis from west to east. A satellite launched from west to east will have the advantage of the additional velocity of the earth's rotation. The effect is maximum at the equator, hence it is most advantageous to launch the satellite from west to east on the equatorial plane.

No. Electrical forces depend upon the nature of the intervening medium while the gravitational forces don’t depend upon the nature of the intervening medium. So, such shielding acts are not possible in case of gravitation i.e., gravity screens are not possible.

Earth moon distance is very small as compared to earth-sun distance. Tidal effect is inversely proportional to the cube of the distance it means it is not governed by inverse square law like the gravitational force (which obeys inverse square law). Hence, tidal effect of moon is larger than that due to the sun.

Whereas the gravitational force depends inversely on the square of the distance, tidal effect depends inversely on the cube of the distance.

In case the size of the space-station becomes large, the forces of gravity will become appreciable, and the astronaut can hope to detect it.

The trajectory of a projectile under gravitational force of earth is a conic section or parabolic or elliptical or its part whose focus must be the centre of the earth. Only (c) option amongst the given curves show the centre of the earth as the focus of trajectory.