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Free fall is a concept in physics that describes the motion of an object under the influence of gravitational force only. The key factor here is that other forces, such as air resistance, are either negligible or completely absent.

Commonly, when objects are in free fall, they experience an acceleration due to gravity which is consistent irrespective of their mass or initial movement. This acceleration is typically denoted as \( g \) and equals approximately \(9.8 \, \text{m/s}^2\) on Earth.

Some important points regarding free fall include:

• The acceleration due to gravity remains constant throughout the fall.
• Objects in free fall will continue to accelerate until they hit the ground or encounter another force, like air resistance.
• In the absence of other forces, all objects fall at the same rate regardless of their masses.

Understanding free fall is crucial as it simplifies many scenarios in physics, making predictions about an object's motion possible through simple calculations.

Acceleration refers to the rate of change of velocity of an object with respect to time. When we discuss acceleration in the context of gravity, it specifically refers to gravitational acceleration, which on Earth is about \(9.8 \, \text{m/s}^2\). This acceleration acts downward towards the center of the Earth.

It's important to understand that acceleration is a vector quantity, meaning it has both magnitude and direction. In our scenario with the two snowballs:

• Both snowballs are subject to the same gravitational acceleration \( g \).
• No matter their initial direction of movement, the acceleration they experience once in the air remains constant and directed downward.
• Gravitational acceleration acts equally on both objects, making their motions predictable if we ignore other forces like air resistance.

While different initial velocities or directions of throw can affect trajectory, they do not alter the acceleration due to gravity itself.

Projectile motion occurs when an object is thrown into the air, and follows a curved path due to the influence of gravity. This movement can be broken down into two components: horizontal and vertical. Understanding these components is vital to grasping how objects move through the air under the force of gravity.

Here's what occurs during projectile motion:

• The horizontal motion remains constant when air resistance is negligible since no horizontal acceleration is acting on the object.
• The vertical motion is where gravity plays its role, accelerating the object downward at \(9.8 \, \text{m/s}^2\).
• The combination of constant horizontal velocity and increasing vertical velocity creates a curved trajectory.

For the snowball thrown horizontally from the roof, it moves with projectile motion, while the snowball thrown straight down simply accelerates due to gravity. Despite different initial motions, the vertical acceleration is consistent, highlighting the role of gravity in projectile motion.