\(T\) is the time period of revolution of a planet revolving around the sun in an orbit of mean radius \(R\). Identify the incorrect graph.
1. | 2. | ||
3. | 4. |
A planet revolving in elliptical orbit has:
(A) | a constant velocity of revolution. |
(B) | the least velocity when it is nearest to the sun. |
(C) | its areal velocity directly proportional to its velocity. |
(D) | its areal velocity inversely proportional to its velocity. |
(E) | to follow a trajectory such that the areal velocity is constant. |
Choose the correct answer from the options given below:
1. | (A) only | 2. | (D) only |
3. | (C) only | 4. | (E) only |
1. | \(6\sqrt{2}~\text{hr}\) | 2. | \(12\sqrt{2}~\text{hr}\) |
3. | \(\frac{24}{2.5}~\text{hr}\) | 4. | \(\frac{12}{2.5}~\text{hr}\) |
Two planets are in a circular orbit of radius \(R\) and \(4R\) about a star. At a specific time, the two planets and the star are in a straight line. If the period of the closest planet is \(T,\) then the star and planets will again be in a straight line after a minimum time:
Assertion (A): | The time period of the revolution of a satellite around a planet is directly proportional to the radius of the orbit of the satellite. |
Reason (R): | Artificial satellites do not follow Kepler's law of planetary motion. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | Both (A) and (R) are False. |
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. The length of the martian year in days is approximately:
(Take \((1.52)^{3/2}=1.87\))
1. | \(344\) days | 2. | \(684\) days |
3. | \(584\) days | 4. | \(484\) days |
Statement I: | The kinetic energy of a planet is maximum when it is closest to the sun. |
Statement II: | The time taken by a planet to move from the closest position (perihelion) to the farthest position (aphelion) is larger for a planet that is farther from the sun. |
1. | Statement I is incorrect and Statement II is correct. |
2. | Both Statement I and Statement II are correct. |
3. | Both Statement I and Statement II are incorrect. |
4. | Statement I is correct and Statement II is incorrect. |
An artificial satellite revolves around a planet for which gravitational force \((F)\) varies with the distance \(r\) from its centre as \(F \propto r^{2}.\) If \(v_0\) is its orbital speed, then:
1. | \(v_{0} \propto r^{-1/2}\) | 2. | \(v_{0} \propto r^{3/2}\) |
3. | \(v_{0} \propto r^{-3/2}\) | 4. | \(v_{0} \propto r\) |