1. Gravity: This is the most significant force. The Earth's gravitational pull constantly tries to pull the rocket back down. To escape this pull, the rocket needs to achieve escape velocity, which is about 11.2 kilometers per second (7 miles per second).

2. Air Resistance: This force, also called drag, is caused by the friction between the rocket and the air as it travels through the atmosphere. Air resistance decreases as the rocket climbs higher and the air becomes thinner.

While gravity is the dominant force, air resistance can still be significant during the initial ascent.

It's important to remember that the rocket isn't simply pushing against these forces. Instead, it uses the principle of thrust, generated by burning fuel and expelling hot gas, to accelerate and overcome the forces of gravity and air resistance.