spacecraft use rockets to get to space
i launched the Rocket ship into the sky
The rocket was so hot it exploded!
The simple subject of the sentence is "rocket."
rocket
The fighter plane began it's inexorable journey to destruction after being hit by a rocket.
rocket
A rocket
The rocket engines ignited, providing the necessary thrust to lift the spacecraft off the launch pad.
Just as it appears in the question ... 'rocket'.
In the sentence "the ball shot straight up, into the air like a rocket", "like a rocket" is a simile. A simile is when something is like something else, but not the something else. This is a describing technique.So in this sentence, it means that the ball moved like a rocket would move.
Rocket oil
It is not feasible to build a rocket ship of wood.