Select all of the answers that apply.

billions of years ago, earth was a very hot place due to

meteorite bombardment
high levels of carbon dioxide and water vapor
earth's strong gravitational pull
cyanobacteria photosynthesis

The answer is letter A. meteorite bombardment.
During the Earth's earliest beginning, it went through a period of catastrophic and intense formation. By 3-8- 4.1 billion years ago, Earth's atmosphere was never the same as today. This is because of its formation during the pre-Cambrian period whereby the Earth formed under so much heat and pressure that it formed as a molten planet.

Earth was bombarded continuously by the remnants of the dust and debris — like asteroids, meteors and comets — until it formed into a solid sphere, pulled into orbit around the sun and began to cool down during the Hellish period (4.5 to 3.8 billion years ago).

 .To know more of this topic, see attached file.

 

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.