Acceleration of a rocket?

Question

Why can a rocket accelerate into space when the force of takeoff remains the same?
-the rocket is on a launch pad

Answer 1

If the thrust is greater than the weight of the rocket, the rocket will accelerate and its acceleration will increase over time if the thrust remains constant.

First, if the thrust is greater than the weight, then there is a net force which means teh rocket must accelerate. As the rocket files out, it is decreasing in mass - the fuel is burned and sent out the exhaust creating the thrust. SInce thrust is constant and mass is decreasing with time, the rocket's acceleration increases with time. Also, as the rocket rises, the force of gravity decreases, so the net force (thrust - weight) increases which means the acceleration should increase.

This is just using F = ma and understanding that if F is constant and m is decreasing in time, a must increase in time to hold F constant.

Answer 2

F=m*a

Which means that

a=F/m.

For a given engine thrust F, the acceleration of the rocket is simply a function of its mass. Since the rocket loses mass with the propellant that leaves the engine, its acceleration will increase unless the engine is cut back. And indeed, many rockets throttle the engines in the first and especially the upper stages to prevent the acceleration of the rocket from reaching a damaging value.

Answer 3

Everything in physics gets back to Newton's second law: F=ma.

If the force is constant, and assuming that mass is constant, acceleration = Force/mass. So as long as acceleration due to the rocket is greater than the acceleration due to gravity, (9.81 m/s^2), the rocket should be able to take off.

Answer 4

If the force at liftoff is sufficient to give the rocket an upward acceleration, the rocket will continue to accelerate - that is, move faster and faster - as long as the force is applied.

Answer 5

in space we do not have the gravitational force of the earth pulling the rocket backwards (hence decreasing its acceleration...)