Physics Question on Gravitational Forces: Bottle rockets being shot vertically and horizontally?

Question

A "bottle rocket" is a type of firework that has a long thin tail that you insert into an empty bottle, to provide a launch platform. One of these rockets is fired with the bottle pointing vertically upward. An identical rocket is fired with the bottle lying on its side, pointing horizontally. In which case does the rocket leave the bottle with the greater acceleration?

Answer 1

In the case of the vertically fired "bottle rocket" the acceleration of gravity directly opposes its vertical ascent acceleration, and this would be true to some extent (vertical component of g) for any vertical angle less than 90° except 0° (horizontal). When fired horizontally (above ground) the "bottle rocket's"

acceleration is unimpeded by gravity.

Answer 2

I'm not a physics major but I believe the bottled rocket pointing upwards would have a greater acceleration because the force of gravity upon the bottle seems less then if it is faced horizontally. Prove me wrong if anyone has a better solution to the problem

Answer 3

Acceleration is Force/mass (Newton's 2nd Law)



The rocket's mass is the same in both cases (say m). Let us assume the force exerted by the rocket's burn is Fr



Horizontally the acceleration is Fr/m



Vertically the weight of the rocket (m*g) opposes the force exerted by the rocket so the nett force on the rocket is Fr-m*g and the acceleration (Fr-m*g)/m or Fr/m-g where g is the acceleration due to gravity (9.81 m/s/s).



Which do you think is bigger?