Difference between negative acceleration and deceleration?

[ASDIC]

Hi,

My Guide for Physics says that negative acceleration is when the velocity increases in the negative direction and decreases in the positive direction (also known as deceleration).

However, my physics professor once told us that negative acceleration and deceleration are 2 different things...

whats the correct definition for both of 'em?

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[LUBDUBB]

Hmmm...I think my physics prof had told us that the correct term is negative acceleration. The word deceleration is not scientific terminology.

 

[Anthropic]

Hi,

My Guide for Physics says that negative acceleration is when the velocity increases in the negative direction and decreases in the positive direction (also known as deceleration).

However, my physics professor once told us that negative acceleration and deceleration are 2 different things...

whats the correct definition for both of 'em?

Deceleration has nothing to do with whether acceleration, a is positive or negative. Deceleration just means the a vector points in the opposite direction of v. If your velocity, v, is to the right, then acceleration to the left (negative acceleration) results in deceleration. If your v vector is to the left (which traditionally denotes the negative), then deceleration (positive acceleration) is to the right, which makes a in the direction of v negative acceleration. This is semantics and only appropriate if you are insistent on using left=negative/right=positive notation.

BUT, it is more logical to make your v vector positive, wherever it points, and decide if you are accelerating or decelerating from there. Negative acceleration and deceleration ARE different, and I would scratch negative acceleration altogether and use a more logical approach to labeling your vector diagrams.

Or, in terms we all understand:

A car is traveling to the left. An increase in speed results in:

a. deceleration
b. negative acceleration
c. no change in speed
d. positive acceleration

 

[princessd3]

Negative acceleration includes deceleration but you can have negative acceleration without deceleration.

Your car is moving right. You hit the brakes. You're negatively accelerating and also decelerating. The acceleration vector points opposite to the velocity vector.

You make a U turn and speed up. You're not decelerating but you're accelerating in the negative direction. Your acceleration vector points in the same direction as velocity vector. It's just that they both point in the negative direction.