Your answer provides a good starting point, but it can be expanded upon for clarity and completeness. Here’s a more detailed explanation of how air resistance and gravity work together to determine the terminal velocity of a falling object:
Explanation of Terminal Velocity:
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Forces Acting on a Falling Object:
- When an object is falling, two primary forces act upon it: gravity and air resistance (also known as drag).
- Gravity pulls the object downward with a force proportional to its mass (F_gravity = m * g, where m is the mass and g is the acceleration due to gravity, approximately 9.81 m/s² on Earth).
- Air resistance acts in the opposite direction of motion and increases as the object's speed increases. It depends on various factors, including the object's shape, cross-sectional area, and the density of the air.
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Acceleration and Velocity:
- Initially, when an object is dropped, gravity causes it to accelerate downward, and the speed of the object increases.
- As the object's speed increases, the air resistance acting against it also increases.
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Achieving Terminal Velocity:
- Eventually, the upward force of air resistance will equal the downward force of gravity. When these two forces balance each other out (F_drag = F_gravity), the net force on the object becomes zero.
- At this point, according to Newton’s first law of motion, the object will no longer accelerate and will fall at a constant speed known as terminal velocity.
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Factors Influencing Terminal Velocity:
- Terminal velocity varies based on the object's mass and surface area. Heavier objects generally have a higher terminal velocity because they require more drag to balance the gravitational force.
- The shape and cross-sectional area play critical roles; more aerodynamic shapes reduce air resistance and allow for higher terminal velocities.
Conclusion:
So, while your statement about air resistance decreasing the rate of acceleration is essentially correct, it’s important to clarify that this force increases until it matches the gravitational force, leading to a constant velocity (terminal velocity) rather than simply reducing acceleration.
Suggested Revision:
"Air resistance acts against the force of gravity on a falling object, slowing down its acceleration as it falls. As the object accelerates, air resistance increases until it equals the gravitational force. When these forces balance, the object reaches terminal velocity, at which point it falls at a constant speed without further acceleration."
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