My bf and I were discussing acceleration. I say that the sign of it depends on your frame of reference, and that it's okay to have it be negative. For example, gravity is generally considered to be negative. He thinks, however, that, since acceleration is a vector, it's always positive. Can you help rectify this? I'm sure there's some way that we're both right. . .
Thanks!
2007-05-15 10:05:27 · 12 answers · asked by Sci Fi Insomniac 6 in Science & Mathematics ➔ Physics
Yes, you are both right!!!
He is right globally and you are right locally, ha-ha.
Here is what I mean:
Acceleration as a vector has a magnitude that can never be negative. However its components can be negative.
Now, the fist sentence is an absolute truth whereas the second sentence is relative because it depends on your choice of reference frame.
Take an example the ball going up with "negative" acceleration. This is true for an observer sitting on the ground. You can always select another reference frame where this same ball is going to have a positive acceleration.
(think about how to select this frame, it is not an inertial one, has to move away from the ground with an acceleration)
2007-05-15 10:24:52 · answer #1 · answered by Leo P 2 · 1⤊ 0⤋
yes technically your right. Some physics textbooks stresses that deceleration is not a physics term used, but rather negative acceleration. In my textbook i remember deceleration was defined something like this When the velocity vector of an object is opposite to the acceleration vector , the object is said to be decelerating. This just means velocity vector is slowing down. That means there is a negative acceleration. So to answer your question, yes both are technically right. but deceleration is rather a fancy term. De is like a prefix of " opposite to". So since acceleration is positive, De-acceleration is opposite of positive or negative acceleration! Use negative acceleration rather than decelerating. Good physics teachers like that.
2016-05-19 02:06:58 · answer #2 · answered by Anonymous · 0⤊ 0⤋
Yes it can be negative. If you throw something up in the air, the acceleration due to gravity is negative. When you put your foot on the brake, the acceleration of your car is negative. Vectors can be & frequently are negative. Tell your BF that he owes you a good dinner.
2007-05-15 10:09:48 · answer #3 · answered by yupchagee 7 · 1⤊ 0⤋
Acceleration is defined as a change in velocity. When its value is positive, the object is increasing velocity. When its negative, the object is decreasing velocity.
When expressed as a vector, negative acceleration is simply in an opposite direction as the velocity.
Hate to say it, but BF is wrong.
2007-05-15 10:11:32 · answer #4 · answered by j c 4 · 1⤊ 0⤋
Slam on the brakes of your car. That is negative acceleration because your speed is now decreasing instead of increasing. So, in terms of semantics you have done something opposite and mathematically expressed your decreasing acceleration requires a negative sign.
2007-05-15 11:16:43 · answer #5 · answered by Joline 6 · 1⤊ 0⤋
acceleration is defined as the change in velocity over time..
if you are speeding up in your car, you are increasing your velocity over time, it a positve acceleration..
and, if you are trying to slow down or stop, you have to decrease your speed, or velocity, that's called a negative accelaration, or deceleration..
acceleration due to gravity is constant.. we choose to label down negative, and up positive.. because acceleration is a vector quantity it has to have a direction. nown, which we label negative.. but you can change you sign, and make everything oppositve. it does not matter.
it all depends on the direction you consider positive here..
2007-05-15 10:24:08 · answer #6 · answered by JAC 3 · 1⤊ 0⤋
Just throw a ball up in the air. While the ball goes up it has a negative acceleration, or else it would go up and up and away!
2007-05-15 10:11:08 · answer #7 · answered by Yahoo! 5 · 1⤊ 0⤋
Its because its a vector that it can be negative, velocity can be negative and acceleration is a based on velocity, if it was based on speed it could not be negative
2007-05-15 10:14:12 · answer #8 · answered by Anonymous · 1⤊ 0⤋
acceleration can have positive and negative values (deceleration).
Negitive acceleration is called deceleration
2007-05-15 10:10:10 · answer #9 · answered by Das 2 · 0⤊ 0⤋
Numbers can be positive or negetive.
Vectors cannot be neither positive nor negative.
Vectors have absolute value, and direction, but no sign.
As it turns out, there's some way that you're both wrong. . .
2007-05-15 11:28:44 · answer #10 · answered by Alexander 6 · 2⤊ 0⤋