When is g (9.8) negative or positive?

In summary, the acceleration due to gravity, g (9.8), can be either negative or positive depending on your choice of coordinate system. If up is positive, then g will be negative, and if down is positive, then g will be positive. As long as you are consistent, the math will work out the same either way.
  • #1
paryann
1
0
when is g (9.8) negative or positive?
i thought that g would be positive when its going towards the ground, and negative when it is being thrown in the air or against gravity.
 
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  • #2
paryann said:
when is g (9.8) negative or positive?
i thought that g would be positive when its going towards the ground, and negative when it is being thrown in the air or against gravity.

You can do it either way. If you drop a rock into a hole ten meters deep, you could say that the rock experienced positive acceleration in the downwards direction and ended up ten meters more deep; or you could say that the rock experienced negative acceleration in the upwards direction and ended up ten meters less high. The math works out the same either way, as long as you're careful to be consistent about whether negative means up or negative means down.
 
  • #3
The acceleration due to gravity is a vector. It has a magnitude of 9.8 m/s², and its direction is downward. Whether or not that is negative or positive depends on your choice of coordinate system. If you had a coordinate system where up is positive then gravity would be negative since its direction is the opposite of your positive direction. If you had a coordinate system where down is positive then gravity would be positive since its direction is the same as your positive direction.

As long as you are careful and consistent you can get the correct answer either way. I tend to choose a positive=up convention.
 

1. When is g (9.8) negative?

Gravity, or the acceleration due to gravity (g), is always a positive value. Therefore, g (9.8) is never negative.

2. Can g (9.8) be positive and negative?

No, g (9.8) is always a positive value. It represents the acceleration due to gravity, which is always directed towards the center of the Earth.

3. Why is g (9.8) sometimes referred to as a negative value?

In some equations, g (9.8) may appear as a negative value, but this is simply to indicate the direction of the acceleration, which is towards the center of the Earth. It does not mean that g (9.8) is actually a negative number.

4. How does the value of g (9.8) affect objects?

The value of g (9.8) represents the acceleration due to gravity, which affects the rate at which objects fall towards the Earth. The greater the value of g (9.8), the faster objects will accelerate towards the Earth.

5. Is the value of g (9.8) constant?

The value of g (9.8) is considered to be a constant on Earth, as it represents the acceleration due to gravity near the surface of the Earth. However, it may vary slightly depending on location and altitude, as well as the mass and distance of the object from the Earth.

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