Question

1. which of the following statements about free fall acceleration on earth is accurate?

it is a constant value of 9.81 m/s².
it is a constant value of -9.81 m/s².
it is only positive when an object is moving upward
it is initially 0 m/s², but increases constantly

Explanation:

The free - fall acceleration on Earth, also known as the acceleration due to gravity, has a magnitude of approximately \(9.81\ m/s^{2}\). The sign (positive or negative) depends on the coordinate system chosen. If we take the upward direction as positive, then the acceleration due to gravity is \(- 9.81\ m/s^{2}\) (since it acts downward). But when we just talk about the value of free - fall acceleration (magnitude), it is a constant \(9.81\ m/s^{2}\) near the surface of the Earth.

• The statement "It is a constant value of \(9.81\ m/s^{2}\)" is correct when considering the magnitude.
• The statement "It is a constant value of \(-9.81\ m/s^{2}\)" is correct in a coordinate system where upward is positive, but it's more about the signed value rather than the general magnitude - based description of free - fall acceleration.
• Free - fall acceleration is always \(g = 9.81\ m/s^{2}\) (in magnitude) near the Earth's surface, regardless of the direction of motion of the object. So, the statement "It is only positive when an object is moving upward" is wrong.
• Free - fall acceleration near the Earth's surface is approximately \(9.81\ m/s^{2}\) and does not start from \(0\ m/s^{2}\) and then increase. So, the statement "It is initially \(0\ m/s^{2}\), but increases constantly" is wrong.

Answer:

It is a constant value of \(9.81\ m/s^{2}\)