Which statement describes planetesimals? Select 3 options.
A) They are the origins of planets.
B) They formed from gas and dust.
C) They were created during the Big Bang.
D) They are believed to have developed in debris disks.
E) They contain 98 percent of matter in the solar system.

Alunar lander is making its descent to moon base i. the lander descends slowly under the retro-thrust of its descent engine. the engine is cut off when the lander is h = 5.5 m above the surface and has a downward speed of 0.8 m/s. with the engine off, the lander is in free fall. what is the speed of the lander just before it touches the surface? the acceleration due to gravity on the moon is 1.6 m/s2.