In 1986, several robotic spacecrafts were sent into space to study the halley's comet. which of these statements best explains why humans should continue to send robotic spacecrafts into space? a. they absorb harmful radiations in space. b. they change weather conditions on earth. c. they discard some myths about objects in space. d. they destroy meteors and comets which might strike earth.

Afaulty model rocket moves in the xy-plane (the positive y direction is vertically upward). the rocket's acceleration has components ax(t) = ? t2 and ay(t) = ? ? ? t, where ? = 2.50 m/s4 , ? = 9.00 m/s2 , and ? = 1.40 m/s3 . at t = 0 the rocket is at the origin and has velocity ~v0 = v0x ? i + v0y ? j with v0x = 1.00 m/s and v0y = 7.00 m/s. (a) calculate the velocity and position vectors as functions of time. (b) what is the maximum height reached by the rocket? (c) sketch the path of the rocket. (d) what is the horizontal displacement of the rocket when it returns to y = 0?