I think it is just going down. Am I right?
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It's not clear if you're asking what direction the acceleration is acting, or if you're asking when it's acting.
The acceleration is always in the same direction (down) and it acts during the entire throw (while it's going up and down).
While going up the acceleration and velocity are in different directions, so the speed decreases. While going down the acceleration and velocity are in the same direction, so the speed increases.
The acceleration is always in the same direction (down) and it acts during the entire throw (while it's going up and down).
While going up the acceleration and velocity are in different directions, so the speed decreases. While going down the acceleration and velocity are in the same direction, so the speed increases.
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The vertical speed at any time t since thrown straight up at Uy is found from Vy = Uy - g t. where g = 9.8 m/s^2.
As you can plainly see, g acts to decelerate the initial speed while the something is still climbing with some upward speed. g is a deceleration because it's acting in the direction opposite to the current speed. And it continues to slow the something until the something reaches maximum height where Vy = 0 = Uy - g t.
Then Harry Potter waves his wand and incantates "velocity reciprocity" and lo and behold that g is now speeding up the something as it falls back toward the ground in a negative direction. So that Vy < 0 while the something falls because the vector is now pointed downward, like the g vector is. And when Vy < 0 and g < 0 they are acting in the same downward directon; so now g is accelerating that something.
So you are right...it's accelerating just going down. But you are wrong, because it's negative acceleration, called deceleration, going up. And you can take that from Hermione, who's a very smart wizard.
As you can plainly see, g acts to decelerate the initial speed while the something is still climbing with some upward speed. g is a deceleration because it's acting in the direction opposite to the current speed. And it continues to slow the something until the something reaches maximum height where Vy = 0 = Uy - g t.
Then Harry Potter waves his wand and incantates "velocity reciprocity" and lo and behold that g is now speeding up the something as it falls back toward the ground in a negative direction. So that Vy < 0 while the something falls because the vector is now pointed downward, like the g vector is. And when Vy < 0 and g < 0 they are acting in the same downward directon; so now g is accelerating that something.
So you are right...it's accelerating just going down. But you are wrong, because it's negative acceleration, called deceleration, going up. And you can take that from Hermione, who's a very smart wizard.
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Only down. When you throw something up, it will travel upwards and obviously not accelerate downward. That would just be silly.
It's only once it stops moving upward, for example, if the object in question changes it's mind, or put mathematically: t(Hammer), that it stops, and from there, it starts acceleratin downward at, indeed 9.8 m/s2.
It's only once it stops moving upward, for example, if the object in question changes it's mind, or put mathematically: t(Hammer), that it stops, and from there, it starts acceleratin downward at, indeed 9.8 m/s2.
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Well, the acceleration is never 9.8, because 9.8 is just a number, not an acceleration.
Oldprof was doing OK until he said, "because it's negative acceleration, called deceleration, going up". which is simply false. Negative acceleration is acceleration in the negative direction. It has *nothing* to do with deceleration.
Technobuff makes the same error.
Oldprof was doing OK until he said, "because it's negative acceleration, called deceleration, going up". which is simply false. Negative acceleration is acceleration in the negative direction. It has *nothing* to do with deceleration.
Technobuff makes the same error.
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Both ways.
While the object is travelling up, the downward accelaration slows it down until it stops.
Then, while the object is travelling down, the downward accelaration speeds it up.
While the object is travelling up, the downward accelaration slows it down until it stops.
Then, while the object is travelling down, the downward accelaration speeds it up.
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Both up and down, but going up the acceleration is negative (deceleration).