What is the value of gravity in free-fall and two-dimensional kinematics?

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Homework Statement

I have just a question to clarify. When an object is in free-fall the gravity is always + 9.81 m/s^2? and also when it is talking about two dimension kinematics gravity is working on an object thrown in the air it is -9.81 m/s^2?

Homework Equations

The Attempt at a Solution

 

[silvashadow]

Yes, when the object is in freefall on Earth, gravity = a = 9.8m/s^2 down. Signs are optional but you could say -9.8n/s^s.
In 2D, the gravity is always 9.8m/s^2 down on the object.

It doesn't matter how the object is moving or thrown, gravity is always down.

 

[Moetasim]

The acceleration due to gravity, denoted as g, is a constant value of 9.81 m/s^2 near the Earth's surface. This value is always positive and acts in the downward direction, regardless of the motion of the object. In the case of free-fall, where an object is only under the influence of gravity, the acceleration will always be equal to g.

In two-dimensional kinematics, the acceleration due to gravity will still be equal to g, but it may act in different directions depending on the motion of the object. For example, if an object is thrown upwards, the acceleration due to gravity will be acting in the downward direction, causing the object to slow down. This is why it is often written as -9.81 m/s^2 in equations, to indicate that it is acting in the opposite direction of the object's motion. However, the magnitude of the acceleration is still 9.81 m/s^2.

It is important to note that the value of g may vary slightly depending on the location and altitude, but for most practical purposes, it can be considered a constant value of 9.81 m/s^2 near the Earth's surface. I hope this clarifies your question.