Identify the force that propels a rocket.
1)The rocket is propelled by the reaction force of the exhaust gasses bouncing off the air molecules outside the rocket.
2)The rocket is propelled because the action force of the rocket on the exhaust gases is greater than the reaction force of the exhaust gasses on the rocket.
3)The rocket is propelled by the reaction force from the particles accelerated out the rear by an action force from the rocket.
4)The rocket is propelled because the action force of the rocket on the exhaust gases is less than than the reaction force of the exhaust gasses on the rocket.
The correct answer is option 3) The rocket is propelled by the reaction force from the particles accelerated out the rear by an action force from the rocket.
Explanation:
When a rocket is launched, it expels exhaust gases at high speeds out of its rear. According to Newton's third law of motion, for every action, there is an equal and opposite reaction. In the case of a rocket, the action force is the force exerted by the rocket on the exhaust gases as it expels them, and the reaction force is the force exerted by the exhaust gases on the rocket in the opposite direction.
The exhaust gases are accelerated out of the rear of the rocket, and as a result, they exert a backward reaction force on the rocket, pushing it forward. This reaction force propels the rocket forward in the opposite direction to the expelled gases.
Therefore, it is the reaction force from the particles accelerated out the rear by an action force from the rocket that propels a rocket.