Question

You friend wonders how a rocket continues to climb into the sky once it is sufficiently high above the surface of Earth so that its expelled gasses no longer push on the surface. How do you respond?

a) The rocket relies on its initial momentum.
b) The rocket's engines keep pushing against the expelled gases.
c) The rocket's energy is conserved, aiding its ascent.
d) The rocket's gravitational pull is stronger at higher altitudes.

Answer 1

To explain how a rocket ascends in space, it's necessary to understand that the engines push against the expelled gases, not against any external surface, following conservation of momentum.

The correct response to this is option (b): The rocket's engines keep pushing against the expelled gases.

Step-by-step explanation:

Your friend is curious about how a rocket continues to climb into the sky once it is high above the Earth's surface.

The correct response to this is option (b): The rocket's engines keep pushing against the expelled gases. This follows the principle of conservation of momentum as described by Newton's third law: for every action, there's an equal and opposite reaction. Thus, when the rocket expels gas backward at high velocity, the rocket itself is pushed forward.

This process does not depend on the atmospheric pressure or any surface to push against; it's equally effective in the vacuum of space.

In fact, since there's no atmospheric drag in space, the rocket's engines can produce greater thrust. Therefore, the misconception that rocket exhaust needs to push against the ground or air is incorrect.