Question

How do space vehicles apply action and reaction forces to blast off?

Answer 1

Newton's first law:

Unless a net external force is applied to it, an object at rest will remain at rest and a moving object will continue to move with the same speed and direction.

$F=ma$ where m =constant mass, F = force, and a = acceleration.

1. Space vehicles apply action and reaction forces to blast off by using rockets to thrust down toward the ground. In reaction, the space vehicle is pushed up into the atmosphere. To make the rocket lift off from the launch pad, the action, or thrust, from the engine must be greater than the mass of the rocket.
2. 
3. Newton's laws of motion apply to rockets. When no force is acting on an object, the first law specifies how it behaves.
4. As a result, rockets remain stationary unless a force is provided to move them. Similarly, once they start moving, they will not stop unless force is supplied to them.
5. According to Newton's second law, the greater the mass of an object, the more force it takes to move it.