The speed at which an object falls is influenced primarily by two forces: gravity and air resistance (drag). Here’s how they work:
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Gravity: This is the force that pulls objects toward the center of the Earth (or any other massive body). The acceleration due to gravity on Earth is approximately \(9.81 , \text{m/s}²\). This means that in the absence of other forces, an object will accelerate downward at this rate.
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Air Resistance: As an object falls, it encounters air resistance (or drag), which opposes the force of gravity. The amount of air resistance depends on several factors:
- Speed: As the object's speed increases, the air resistance also increases.
- Surface Area: A larger surface area increases air resistance.
- Shape: The shape of the object can affect how air flows around it, impacting the amount of drag. For instance, a flat piece of paper will fall slower than a similarly sized ball due to increased drag.
- Density of the Air: At higher altitudes where air is less dense, there is less air resistance.
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Terminal Velocity: When an object falls, it will accelerate until the force of air resistance equals the force of gravity. At this point, it stops accelerating and falls at a constant speed, known as terminal velocity. The terminal velocity varies depending on the size, shape, and mass of the object.
In summary, while gravity pulls an object downwards, air resistance works against that force, and the combination of these two influences determines how fast an object falls.