Final answer:
The vertical ascent of a rocket involves overcoming the force of gravity through the expulsion of exhaust gases which generate thrust. The rocket will accelerate as it loses mass due to fuel consumption and will eventually decelerate and stop momentarily at its peak before starting to fall back to Earth.
Step-by-step explanation:
When describing the motion of a rocket ascending vertically after being launched, it is crucial to understand the forces at play. The rocket starts by releasing a burst of explosive energy, propelling it upwards. During its ascent, the rocket is under the influence of gravity, which consistently works against its motion, decreasing its acceleration. As the rocket moves up, it expels exhaust gases downwards, which, by Newton's third law, generates the thrust needed for the rocket to continue ascending.
The rocket's motion can be observed in two phases: the initial launch phase, where it predominantly accelerates upwards due to the thrust being greater than the force of gravity, and the latter phase as it approaches its highest point, where deceleration occurs due to gravity. However, the concept of a commonly held misconception that rocket exhaust pushes on the ground should be dispelled; the thrust a rocket feels is actually greater in outer space than in the atmosphere, as gases are easier to expel into a vacuum.
As the rocket ascends, it also loses mass because it is burning fuel. This loss in mass means that the same amount of force will produce a greater acceleration over time, according to Newton's second law of motion (F=ma), allowing the rocket to speed up as it gets lighter. After the engines cut off, the rocket will eventually reach a point where its vertical velocity is zero before starting its descent back to Earth, influenced solely by gravity, following a parabolic trajectory if we ignore air resistance.