General question- when do you use NEGATIVE for 9.8m/s^2?
Even when the questions says "an object is thrown up in the air from top of the building, on its way down, it misses the building and falls to the ground below."
If you do use a negative value, why is that?
Negative value for what? Normally, I make upwards positive.
g will be negative (downwards)
initial velocity is positive (upwards).
It is because g oppose acceleration meaning that it becoms negative acceleration
To determine when to use a negative value for acceleration due to gravity (-9.8 m/s^2), we need to understand the concept of a coordinate system and the direction of positive and negative values.
In a standard coordinate system, the positive direction is typically defined as upwards, and the negative direction is downwards. In the given scenario, an object is thrown up in the air from the top of the building and then falls back to the ground below. So, if we take the top of the building as the origin of our coordinate system, the object's initial velocity would be positive (upwards) when it is thrown up, and its final velocity would be negative (downwards) when it falls back down towards the ground.
Since acceleration due to gravity always acts downwards, we assign it a negative value (-9.8 m/s^2) in this case. By using the negative sign, we account for the fact that gravity is pulling the object towards the ground, opposing its upward motion.
Therefore, when solving problems involving the motion of objects thrown up and falling back down, such as in the given scenario, it is appropriate to use a negative value (-9.8 m/s^2) for acceleration due to gravity to correctly describe the downward acceleration a falling object experiences.