Question

Multiple choice: Which one of the following statements is true?

(a) There is still no direct evidence that a comet or asteroid impact helped cause the Cretaceous–Paleogene (i.e., Cretaceous-Tertiary) extinction during which the dinosaurs perished because no matching crater has yet been found.

(b) The collision of Comet Shoemaker-Levy 9 with Jupiter dramatically illustrated the amount of energy that can be released when an asteroid or comet hits a planet.

(c) In principle, nothing can be done to prevent collisions of asteroids with Earth, so we might as well not worry about them too much.

(d) Comets are like icy asteroids in composition, but they come primarily from regions beyond Neptune’s orbit such as the Kuiper belt and the Oort cloud.

(e) Meteor showers are produced when a cluster of stars falls through Earth’s atmosphere.

Multiple choice: Which one of the following best describes the reason Pluto was demoted from being a genuine planet and promoted to the status of “dwarf planet”?

(a) It orbits its center of mass with its main moon, Charon.

(b) It is too small and is thus not quite spherical.

(c) Its orbit sometimes brings it closer to the Sun than Neptune.

(d) Its orbit is far more inclined than those of the other planets.

(e) It has not cleared most other objects from its neighborhood.

Multiple choice: Pluto has an orbital period of roughly 250 years. In 1989 Pluto was closer to the Sun than Neptune was. During which one of the following years will Pluto have the highest orbital speed?

(a) 2015.

(b) 2051.

(c) 2114.

(d) 2176.

(e) 2239.

Answer 1

Answer to 1st mcq : (d), other answers are false.

Answer to 2nd mcq : (e) It has not cleared most other objects from it's neighbourhood, other reasons are not the reason for pluto to be given the status of drawf planet.

Answer to 3rd mcq : (e) 2239, According to Kepler's 2nd law, the area swept by the radius of elliptical orbit is equal for equal interval of time. Hence the orbital speed of planet is maximum when it is closest to sun. The period of pluto is 250 years i. e. It will come to the same position after 250 years. Given that pluto was nearest to sun in 1989 hence having maximum speed. And so in 1989 + 250 = 2239 years Pluto will come again closest to sun and have maximum orbital speed.