The Constant Speed of Free Falling Objects

In summary, when an object free falls, it experiences two types of acceleration - proper acceleration and coordinate acceleration. Proper acceleration, measured by an accelerometer, is always zero for a free falling object. However, coordinate acceleration, which is the second derivative of the coordinate position, may not be constant and can even be negative in certain situations, such as near a black hole. Therefore, the speed of a free falling object may not be constant in non-inertial frames.
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isyang94
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When an object free falls, its accerleration is constant, but does its speed change? If so is it practicing uniform or non uniform motion?
 
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That depends what you mean by acceleration. In relativity there are two distinct concepts called acceleration. One is proper acceleration, which is the acceleration measured by an accelerometer. The other is coordinate acceleration, which is the second time derivative of the coordinate position.

An object in free-fall has a proper acceleration of 0, so its speed is constant in any local inertial frame.

In non-inertial frames it may have a non-zero coordinate acceleration so its speed would not be constant in that coordinate system.
 
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Acceleration as in the gravity 9.8m/s/s
thanks for the reply
 
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isyang94 said:
When an object free falls, its accerleration is constant, but does its speed change? If so is it practicing uniform or non uniform motion?
Why do you mistakenly conclude that a free falling object's coordinate acceleration is always constant?

Consider a radially free falling test object approaching a black hole as modeled by the Schwarzschild solution, its coordinate acceleration is not constant and may in some cases and 'locations' even be negative (e.g. directed away from the black hole).
 
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FAQ: The Constant Speed of Free Falling Objects

What is the constant speed of free falling objects?

The constant speed of free falling objects is the rate at which an object falls towards the ground due to the force of gravity, without any other forces acting on it. This speed is approximately 9.8 meters per second squared, and is also known as the acceleration of gravity.

Why do all free falling objects have the same constant speed?

All free falling objects have the same constant speed because they are all affected by the same acceleration of gravity, regardless of their mass or size. This means that regardless of their weight, all objects will fall towards the ground at the same rate.

Does the constant speed of free falling objects change?

No, the constant speed of free falling objects does not change as long as there are no other forces acting on the object. This means that in a vacuum, where there is no air resistance, the object will continue to fall at a constant speed until it reaches the ground.

How does air resistance affect the constant speed of free falling objects?

Air resistance can affect the constant speed of free falling objects by slowing down the object's descent. As an object falls through the air, it experiences a force in the opposite direction of its motion, which can reduce its speed. This is why objects with a larger surface area, such as a feather, fall slower than objects with a smaller surface area, such as a rock.

Can the constant speed of free falling objects be greater than 9.8 meters per second squared?

Yes, the constant speed of free falling objects can be greater than 9.8 meters per second squared if the object is falling in a location with a stronger gravitational pull, such as on a different planet. The acceleration of gravity can vary depending on the mass and distance between objects. However, on Earth, the acceleration of gravity is always approximately 9.8 meters per second squared.

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