Scientists launch a rocket, and they monitor its acceleration and the force exerted by its engines. As the rocket gets higher, the monitors show that the acceleration of the rocket is increasing but the force exerted stays the same. How do Newton’s laws explain why the scientists could expect this to happen?

Question

The total force stays the same, but the action force is increasing as the reaction decreases.
The mass of the rocket decreases as fuel is burned, so the acceleration increases.
The inertia of the rocket increases, which reduces the force needed to change its speed.
The reaction force is increasing as fuel is burned, which causes a greater acceleration.

Answer 1

The correct explanation for why the acceleration of the rocket is increasing while the force exerted by its engines remains constant is:

The mass of the rocket decreases as fuel is burned, so the acceleration increases.

This can be explained using Newton’s second law of motion, which states that the acceleration of an object is equal to the net force acting on it divided by its mass (F = ma).

In the case of the rocket:

1. The force exerted by the engines remains constant.
2. As the rocket ascends, it burns fuel, which means the total mass of the rocket decreases.
3. Since the force stays the same and the mass decreases, the acceleration must increase to satisfy the equation F = ma.

Therefore, as the rocket sheds mass, it accelerates more for the same amount of thrust produced by its engines.