No. You have to specify a coordinate system. I can choose a coordinate system which makes [down] positive and [up] negative. As long as I am consistent with my coordinates, the acceleration is positive.
Just another technicality.
Originally posted by: Cooler
Originally posted by: Wnh5001
Magnitude is a positive quantityOriginally posted by: Cooler
Originally posted by: Wnh5001
Originally posted by: Cooler
Originally posted by: Wnh5001
a particle reaches it max height t= 2 seconds, what is the magnitude of its acceleration?
|hint|- the t=2 seconds doesnt mean anything =S, choose wisely,
a)19.6
b)9.81
c)0
d)-9.81
-9.81 the pull of graity in the negitive direction.
INCORRECT!
Is the particle on earth? all falling objects(on earth) have that acceleration in the Y vector.
Well in that case it would have to be 9.81 if you want to be technical about it but it will go +180 of the original angle.
Magnitude = (Ax^2+AY^2)^(1/2)
which would be in this 9.81
But its acceleration is negitive.
Originally posted by: eits
how the hell is this a 5-paged thread? the answer is c. it's over. done. no debate. let it die.
answer = c.... 0.
the end.
Originally posted by: Titan
Originally posted by: Mo0o
But if you shot pictures of the bullet as it went to the apex then back down and had the height/time data, you should be abel to derive an acceleration can't you? Pulling out hte pictures of the bullet at its apex isn't enough evidence to say whetheri ts accelerating or not.
Ive done this in physics lab where we toss a ball in the air and had a video camera. You can derive the time and height of the ball and calculate a trajectory which lets you find acceleration
You and I are literally down to what we each think the word "acceleration" means. According to the mathematic definition you seem to be correct. This could go on forever. You think it is a cause, and I think it is an effect, caused by forces. I think I've been over this before. To me, forces cause acceleration. And there are questions about reference framse. Right now my butt is not accelerating though my chair despite the force of gravity, due to counteracting forces. But that will soon change because I am tired of discussing this and have made it very clear that I interpreted the language differently. And at the end of the day, we all have to intrepret what Cheny meant when he said he shot that guy in the face.
Originally posted by: Mo0o
Is this ownage of the year material?
Originally posted by: Atomicus
Originally posted by: Mo0o
Is this ownage of the year material?
I think this thread clearly separated engineering and non-engineering material that roams in this forum.
Originally posted by: Titan
Eeezee, I know all this. You don't have to give me remedial physics. I have condeded that 9.8 looks ok on paper. But I honestly ask you what use is that information to an engineer, or anybody for that matter? I look for the deeper meaning, which has to do with forces. It tells us there is a force we need to know about.
Or to answer your other statement, how do you measure acceleration? Predict it with a formula, or use an instrument?
I'm looking at the big picture, and remembering the fundamentals of how science works.
I say the question is ambiguous. But people are, so you need to know them.
Originally posted by: Mo0o
Originally posted by: Atomicus
Originally posted by: Mo0o
Is this ownage of the year material?
I think this thread clearly separated engineering and non-engineering material that roams in this forum.
engineers dont experience gravitY?
Originally posted by: Titan
Originally posted by: Mo0o
In the end the math doesn't lie:
X=VoT + .5 AT^2
dX/dT = V = Vo + AT
dV/dT = A
No, the language lies. Acceleration, to me, is a measurement of phenomena, motion. I don't care if you think i'm right or wrong. The point out of all this is that our language is so inadequate that we need more insight from the asker of the question. If they threw the word "resulting" acceleration in there, it would change things, right? I see that word as implied.
If you were an engineer and asked this question, you would make sure and ask for clarification. Otherwise people may die.
I'm looking at it from the practical slant. At rest, what does an accelerometer measure?
Originally posted by: virtualgames0
Originally posted by: JujuFish
Originally posted by: virtualgames0
Originally posted by: JujuFish
Originally posted by: ledjani
Well I believe the answer is 0. The derivative of the velocity is acceleration. Thus whenever the graph of the velocity reaches its max, the derivative is 0. Thus the acceleration is 0. Because it is at rest acceleration wise, it has reached the top, and it isn't going up or down anymore.
If the graph of velocity has a local maximum, then acceleration is not constant. If that is the case, then yes, acceleration would be zero at that local maximum.
Nope the acceleration is still constant as the force acting on it is constant.
First, I was speaking in general. If a graph of velocity is curved, then acceleration is not constant. That is the type of graph referred to in ledjani's post. Second, you don't know what forces are acting on it, so you cannot make that claim regarding the OP. Third, notice the "if" in my original statement.
Yeah you're right about the curved graph. I see what you were saying before.
Originally posted by: bonkers325
would have to be D, since it is the only negative quantity available. you are given no other infomation, so applying formulas and the such would be useless. if the acceleration were not negative, the particle would never stop.
Originally posted by: Mo0o
Originally posted by: bonkers325
would have to be D, since it is the only negative quantity available. you are given no other infomation, so applying formulas and the such would be useless. if the acceleration were not negative, the particle would never stop.
it asks for magnitude, which is a positive value
Originally posted by: bonkers325
Originally posted by: Mo0o
Originally posted by: bonkers325
would have to be D, since it is the only negative quantity available. you are given no other infomation, so applying formulas and the such would be useless. if the acceleration were not negative, the particle would never stop.
it asks for magnitude, which is a positive value
if the acceleration is anything but negative, then the particle would never reach a -true- maximum height.
if acceleration > 0, then the particle will always be increasing in speed - this means that it will never reach maximum height.
if acceleration < 0, then the particle will reach a velocity of 0 m/s at some point in time, where it will begin to fall downward. that point in time (t=2s) is the apex which is the maximum height.
Originally posted by: bonkers325
Originally posted by: Mo0o
Originally posted by: bonkers325
would have to be D, since it is the only negative quantity available. you are given no other infomation, so applying formulas and the such would be useless. if the acceleration were not negative, the particle would never stop.
it asks for magnitude, which is a positive value
if the acceleration is anything but negative, then the particle would never reach a -true- maximum height.
if acceleration > 0, then the particle will always be increasing in speed - this means that it will never reach maximum height.
if acceleration < 0, then the particle will reach a velocity of 0 m/s at some point in time, where it will begin to fall downward. that point in time (t=2s) is the apex which is the maximum height.
Originally posted by: blueshoe
Originally posted by: bonkers325
Originally posted by: Mo0o
Originally posted by: bonkers325
would have to be D, since it is the only negative quantity available. you are given no other infomation, so applying formulas and the such would be useless. if the acceleration were not negative, the particle would never stop.
it asks for magnitude, which is a positive value
if the acceleration is anything but negative, then the particle would never reach a -true- maximum height.
if acceleration > 0, then the particle will always be increasing in speed - this means that it will never reach maximum height.
if acceleration < 0, then the particle will reach a velocity of 0 m/s at some point in time, where it will begin to fall downward. that point in time (t=2s) is the apex which is the maximum height.
You are correct, the acceleration is negative. The magnitude of the acceleration is positive.
Originally posted by: Eeezee
Originally posted by: Titan
Originally posted by: Mo0o
But if you shot pictures of the bullet as it went to the apex then back down and had the height/time data, you should be abel to derive an acceleration can't you? Pulling out hte pictures of the bullet at its apex isn't enough evidence to say whetheri ts accelerating or not.
Ive done this in physics lab where we toss a ball in the air and had a video camera. You can derive the time and height of the ball and calculate a trajectory which lets you find acceleration
You and I are literally down to what we each think the word "acceleration" means. According to the mathematic definition you seem to be correct. This could go on forever. You think it is a cause, and I think it is an effect, caused by forces. I think I've been over this before. To me, forces cause acceleration. And there are questions about reference framse. Right now my butt is not accelerating though my chair despite the force of gravity, due to counteracting forces. But that will soon change because I am tired of discussing this and have made it very clear that I interpreted the language differently. And at the end of the day, we all have to intrepret what Cheny meant when he said he shot that guy in the face.
In other words, you fvcked up your first answer and need to endlessly backpedal on semantics in order to make yourself feel better.
Originally posted by: bonkers325
Originally posted by: blueshoe
Originally posted by: bonkers325
Originally posted by: Mo0o
Originally posted by: bonkers325
would have to be D, since it is the only negative quantity available. you are given no other infomation, so applying formulas and the such would be useless. if the acceleration were not negative, the particle would never stop.
it asks for magnitude, which is a positive value
if the acceleration is anything but negative, then the particle would never reach a -true- maximum height.
if acceleration > 0, then the particle will always be increasing in speed - this means that it will never reach maximum height.
if acceleration < 0, then the particle will reach a velocity of 0 m/s at some point in time, where it will begin to fall downward. that point in time (t=2s) is the apex which is the maximum height.
You are correct, the acceleration is negative. The magnitude of the acceleration is positive.
:thumbsup:
Originally posted by: ledjani
Even though all the feedback, I am going to stick with my answer being 0. When the original poster gets his exam back, I would appreciate it, if he could tell us the answer so we can put an end to this.
Originally posted by: ledjani
Even though all the feedback, I am going to stick with my answer being 0. When the original poster gets his exam back, I would appreciate it, if he could tell us the answer so we can put an end to this.