Satellites orbiting the earth have a finite life and sometimes debris of satellites fall to the earth. This is because:
1. | the solar cells and batteries in satellites run out. |
2. | the l2. of gravitation predict a trajectory spiralling inwards.awst |
3. | of viscous forces causing the speed of the satellite and hence height to gradually decrease. |
4. | of collisions with other satellites. |
Both the earth and the moon are subject to gravitational force of the sun. As observed from the sun, the orbit of the moon:
1. | will be elliptical |
2. | will not be strictly elliptical because the total gravitational force on it is not central |
3. | is not elliptical but will necessarily be a closed curve |
4. | deviates considerably from being elliptical due to the influence of planets other than the earth |
In our solar system, the interplanetary region has chunks of matter (much smaller in size compared to planets) called asteroids. They:
1. | will not move around the sun, since they have very small masses compared to the sun. |
2. | will move in an irregular way because of their small masses and will drift away into outer space. |
3. | will move around the sun in closed orbits but not obey Kepler’s laws. |
4. | will move in orbits like planets and obey Kepler’s laws. |
Choose the wrong option.
1. | Inertial mass is a measure of the difficulty of accelerating a body by an external force whereas gravitational mass is relevant in determining the gravitational force on it by an external mass. |
2. | That the gravitational mass and inertial mass are equal is an experimental result. |
3. | That the acceleration due to gravity on the earth is the same for all bodies is due to the equality of gravitational mass and inertial mass. |
4. | Gravitational mass of a particle-like proton can depend on the presence of neighbouring heavy objects but the inertial mass cannot. |
Particles of masses 2M, m and M are respectively at points A, B and C with . The mass m is much-much smaller than M and at time t = 0, they are all at rest as given in the figure. At subsequent times before any collision takes place,
1. m will remain at rest.
2. m will move towards M.
3. m will move towards 2M.
4. m will have oscillatory motion.
The following are the given statements:
a. | Acceleration due to gravity decreases with increasing altitude. |
b. | Acceleration due to gravity increases with increasing depth (assume the earth to be a sphere of uniform density). |
c. | Acceleration due to gravity increases with increasing latitude. |
d. | Acceleration due to gravity is independent of the mass of the earth. |
Choose the correct alternatives:
1. (b, d)
2. (a, c)
3. (c, d)
4. (a, c, d)
If the law of gravitation, instead of being inverse square law, becomes an inverse cube law:
a. | planets will not have elliptic orbits. |
b. | circular orbits of planets are not possible. |
c. | the projectile motion of a stone thrown by hand on the surface of the earth will be approximately parabolic. |
d. | there will be no gravitational force inside a spherical shell of uniform density. |
Choose the correct alternatives:
1. (a, d)
2. (a, c)
3. (c, d)
4. (b, d)
If the mass of the sun were ten times smaller and gravitational constant G were ten times larger in magnitude. Then,
a. | walking on the ground would become more difficult. |
b. | the acceleration due to gravity on the earth will not change. |
c. | raindrops will fall much faster. |
d. | aeroplanes will have to travel much faster. |
Choose the correct alternatives:
1. (a, b, c)
2. (a, d)
3. (b, c, d)
4. (a, c, d)
If the sun and the planets carried huge amounts of opposite charges, then:
a. | all three of Kepler’s laws would still be valid |
b. | only the third law would be valid |
c. | the second law would not change |
d. | the first law would still be valid |
Which of the above statements is/are correct?
1. (a, b, c)
2. (a, d)
3. (b, c, d)
4. (a, c, d)
There have been suggestions that the value of the gravitational constant G becomes smaller when considered over a very large time period (in billions of years) in the future. If that happens, for our earth,
a. | nothing will change |
b. | we will become hotter after billions of years |
c. | we will be going around but not strictly in closed orbits |
d. | after a sufficiently long time, we will leave the solar system |
Choose the correct alternatives:
1. (a, c)
2. (a, d)
3. (c, d)
4. (a, b)