Free Fall

Definition

Free fall refers to the motion of an object when it is falling solely under the influence of gravity, with no other forces acting on it, such as air resistance. In this state, all objects accelerate towards the Earth at the same rate, approximately $$9.81 \, \text{m/s}^2$$, regardless of their mass. This concept is critical in understanding gravitational potential energy, gravitational fields, motion in one dimension, and acceleration.

5 Must Know Facts For Your Next Test

1. In free fall, all objects experience the same acceleration regardless of their mass or shape.
2. Air resistance can significantly alter the behavior of falling objects, but in a vacuum, they will all fall at the same rate.
3. The distance fallen by an object in free fall can be calculated using the equation $$d = \frac{1}{2}gt^2$$, where $$d$$ is distance, $$g$$ is acceleration due to gravity, and $$t$$ is time.
4. Free fall can occur on any planet with a gravitational pull, but the rate of acceleration will vary depending on the planet's mass and radius.
5. When analyzing free fall, it’s important to distinguish between instantaneous velocity (the speed at a specific moment) and average velocity (the total distance divided by total time).

Review Questions

• How does free fall demonstrate that all objects accelerate at the same rate regardless of their mass?
  • Free fall illustrates that when objects are dropped from the same height in a vacuum, they accelerate at the same rate due to gravity alone. This means that whether you drop a feather or a bowling ball, both will hit the ground simultaneously if air resistance is negligible. This principle challenges everyday assumptions about weight affecting speed and reinforces that gravity affects all masses equally.
• Explain how free fall relates to gravitational potential energy and how this energy changes as an object falls.
  • As an object falls freely under gravity, its gravitational potential energy decreases while its kinetic energy increases. Initially, when the object is at a height $$h$$, it has maximum potential energy given by $$PE = mgh$$. As it falls and reaches lower heights, this energy transforms into kinetic energy until just before impact when its potential energy is minimal and kinetic energy reaches its peak. This interplay between potential and kinetic energy is fundamental in understanding motion under gravity.
• Evaluate the effects of air resistance on free fall and how it alters the motion of falling objects in real-world scenarios.
  • Air resistance plays a crucial role in determining how objects behave during free fall in real-world conditions. While objects in a vacuum fall freely without resistance and accelerate uniformly at $$9.81 \, \text{m/s}^2$$, those in Earth's atmosphere experience drag forces that depend on their shape and speed. This can lead to phenomena like terminal velocity, where an object's weight balances with air resistance, resulting in no further acceleration. Understanding these effects is essential for practical applications such as skydiving or designing parachutes.

Related terms

Acceleration due to Gravity: The constant acceleration experienced by an object in free fall near the Earth's surface, typically denoted as $$g$$ and equal to approximately $$9.81 \, \text{m/s}^2$$.

Gravitational Potential Energy: The energy stored in an object due to its position in a gravitational field, calculated using the formula $$PE = mgh$$, where $$m$$ is mass, $$g$$ is acceleration due to gravity, and $$h$$ is height.

Terminal Velocity:

The maximum velocity an object reaches when the force of gravity is balanced by the drag force of air resistance, resulting in no further acceleration.