Final answer:
The two forces acting on the space shuttle in a free fall when returning from space are the force due to gravity and the force from air resistance. These two forces are respectively responsible for pulling the shuttle towards Earth and opposing its descent.
Step-by-step explanation:
The two forces acting on the space shuttle as it returns from space in a free fall are 1) Force due to gravity and 2) force from air resistance.
When a space shuttle is in orbit, it is essentially in a continuous state of free fall towards Earth, resulting in a lack of apparent gravity within the shuttle. This concept can also be applied when a shuttle or any other object is returning from space. The force due to gravity acts downwards, pulling the shuttle towards Earth, while the force from air resistance opposes this motion, effectively reducing the net force acting on the shuttle.
According to Newton's second law of motion, the net force is the total forces acting on an object minus any opposing forces. In this scenario, the space shuttle is experiencing a downward gravitational force of 1200 N opposed by 1000 N of air resistance. Therefore, the net force acting on the shuttle is 200 N in the downward direction, which would result in a deceleration of the space shuttle as it plunges through the atmosphere due to this unbalanced force.