Ineed ! a 2.0 kilogram toy cannon is at rest on a frictionless surface. a. remote triggering device causes a 0.005 kilogram projectile to be fired from the cannon. which of the following equations best describes this system after the cannon is fired? a) speed of cannon + speed of projectile=0b) mass of cannon + mass of projectile = 0 c) velocity of cannon + velocity of projectile=0d)momentum of cannon + momentum of projectile= 0 d is the correct answer but i need an explanation of why it is the right answer

D) momentum of cannon + momentum of projectile= 0

Explanation:

The law of conservation of momentum states that the total momentum of an isolated system is constant.

In this case, the system cannon+projectile can be considered as isolated, because no external forces act on it (in fact, the surface is frictionless, so there is no friction acting on the cannon). Therefore, the total momentum of the two objects (cannon+projectile) must be equal before and after the firing:

But the initial momentum is zero, because at the beginning both the cannon and the projectile are at rest:

So the final momentum, which is sum of the momentum of the cannon and of the projectile, must also be zero:

the answer for apex is the lowest

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.