Final answer:
The normal acceleration of an object thrown horizontally from a tower and in free fall at any time t is the acceleration due to gravity, g, which averages 9.8 m/s² on Earth.
Step-by-step explanation:
The free fall acceleration of an object in orbit at a certain time t from the top of a tower when thrown horizontally with an initial velocity is constant due to the acceleration due to gravity. Ignoring air resistance, any object in free fall on Earth experiences this constant acceleration, which has an average value of 9.8 m/s². This is represented by the symbol g. If air resistance is negligible and the object is thrown horizontally, the only acceleration affecting it is the acceleration due to gravity, acting downwards towards the center of the Earth. Therefore, the normal acceleration of the object in free fall at any time t will be g. When calculating any aspects of the object's motion, assuming we define downwards as the positive direction, the acceleration a would be +g.