Kinematics Equations (2 Problems)

[Johnny_07]

Homework Statement

In solving a kinematic equation for x, which has a negative acceleration, is x necessarily negative?

A classmate states that a negative acceleration always means that a moving object decelerating. Is this statement true? Explain.

Homework Equations

The Attempt at a Solution

 

[solarwind]

Homework Statement

In solving a kinematic equation for x, which has a negative acceleration, is x necessarily negative?

A classmate states that a negative acceleration always means that a moving object decelerating. Is this statement true? Explain.

Homework Equations

The Attempt at a Solution

No, depends on reference. You can say gravity has a negative acceleration in the y prime, but a falling object is accelerating. The correct term is negative acceleration, not decelerating.

Note: I could be wrong.

 

[Johnny_07]

Thanks for the help, but it's two problems in my book, and those are the exact words. So I don't know.

 

[solarwind]

Thanks for the help, but it's two problems in my book, and those are the exact words. So I don't know.

For your first question, what is x? Is it displacement, velocity or what?

 

[Johnny_07]

I have no idea. I believe it's displacement, if I'm not mistaken. My teacher and the textbook is really vague and not clear at all :(

 

[solarwind]

I have no idea. I believe it's displacement, if I'm not mistaken. My teacher and the textbook is really vague and not clear at all :(

Haha! I know how that is...

The answer is NO. This is because x could have a positive displacement and could also have a negative acceleration (slowing down) at the same time. Example, you roll a ball on the floor. It moves away from you (positive displacement) but is also slowing down (negative acceleration).

Again, I could be wrong, I'm only in last year of high school physics.

 

[Johnny_07]

Alright, I'll take that into consideration.
Thanks a lot again! :) Really helped!