Question

how does newtons third law explain how a rocket is launched upward?
a. as the fuel burns, the rockets mass decreases, allowing it to fly faster and faster.
b. when the rockets speed increases, the amount of force needed to move it decreases.
c. as the rocket accelerates upward, the air resistance pushing against the rocket decreases.
d. gases from burning fuel are pushed out of the bottom of the rocket, and these gases push back on the rocket with an equal amount of force.

Explanation:

Newton's third law states that for every action, there is an equal and opposite reaction. When a rocket launches, the burning fuel creates gases that are pushed out (action) from the bottom of the rocket. According to the third law, these gases push back on the rocket (reaction) with an equal amount of force, which propels the rocket upward.

• Option A is about mass and speed (related to Newton's second law \(F = ma\) where \(a=\frac{F}{m}\), if \(m\) decreases and \(F\) is constant, \(a\) increases).
• Option B is incorrect as force \(F = ma\) (Newton's second law), if speed increases (assuming acceleration \(a\) is non - zero), and mass \(m\) is constant, force \(F\) increases.
• Option C is about air resistance and acceleration (more related to forces acting on the rocket during motion rather than the launch mechanism based on Newton's third law).

Answer:

D. Gases from burning fuel are pushed out of the bottom of the rocket, and these gases push back on the rocket with an equal amount of force.