A Comeback Post (Assignment related)

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What is the acceleration of a vertically thrown object at the peek of its path?

$9.8ms^{-2}$
3
75%
$0ms^{-2}$
1
25%
 
Total votes: 4

Asif Hossain
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A Comeback Post (Assignment related)

Unread post by Asif Hossain » Thu Jun 24, 2021 10:54 pm

For HSC first year in the first week (surely everybody has submitted that by now) there was a problem stating:
What is the acceleration of a vertically thrown object at the peek of its path?
Somebody say it is $0ms^{-2}$ some say it is $9.8ms^{-2}$
I am on the side of $9.8ms^{-2}$ here is my reason:
At the peek the object is going to be a free falling object so at time $t$ its velocity $v=v_0 +gt$
So, at any moment the acceleration should be $\frac{d}{dt}(v_0 +gt) \Rightarrow g=9.8ms^{-2}$
Hmm..Hammer...Treat everything as nail

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Mehrab4226
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Re: A Comeback Post (Assignment related)

Unread post by Mehrab4226 » Fri Jun 25, 2021 10:10 am

I am also on the side of $9.8 ms^{-2}$, because if the acceleration is $0$. Then the object is not supposed to move down. But it does move down. So it has acceleration.
The Mathematician does not study math because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful.
-Henri Poincaré

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Anindya Biswas
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Re: A Comeback Post (Assignment related)

Unread post by Anindya Biswas » Fri Jun 25, 2021 8:08 pm

Acceleration is the second derivative of position with respect to time.
The position of the object is given by,
$y(t)=v_0t-\frac12gt^2$
$\Rightarrow y''(t)=-g$

Some confusion is arising that since the object was moving upwards, there should be an upward force acting on that object, and the gravitational force cancelled that force and the total force should be zero.
But the problem is, there was no force acting on that thing upwards. The upward force acted when it was in our hand. As soon as it left the ground, all upward forces stopped acting and the object moved upward for its inertia. So gravitational force never cancelled anything, it was the only force acting there.
"If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is."
John von Neumann

Asif Hossain
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Re: A Comeback Post (Assignment related)

Unread post by Asif Hossain » Sat Jun 26, 2021 10:43 pm

Anindya Biswas wrote:
Fri Jun 25, 2021 8:08 pm
Acceleration is the second derivative of position with respect to time.
The position of the object is given by,
$y(t)=v_0t-\frac12gt^2$
$\Rightarrow y''(t)=-g$

Some confusion is arising that since the object was moving upwards, there should be an upward force acting on that object, and the gravitational force cancelled that force and the total force should be zero.
But the problem is, there was no force acting on that thing upwards. The upward force acted when it was in our hand. As soon as it left the ground, all upward forces stopped acting and the object moved upward for its inertia. So gravitational force never cancelled anything, it was the only force acting there.
-g or g?? :|
Hmm..Hammer...Treat everything as nail

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Anindya Biswas
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Re: A Comeback Post (Assignment related)

Unread post by Anindya Biswas » Sat Jun 26, 2021 11:48 pm

Asif Hossain wrote:
Sat Jun 26, 2021 10:43 pm
Anindya Biswas wrote:
Fri Jun 25, 2021 8:08 pm
Acceleration is the second derivative of position with respect to time.
The position of the object is given by,
$y(t)=v_0t-\frac12gt^2$
$\Rightarrow y''(t)=-g$

Some confusion is arising that since the object was moving upwards, there should be an upward force acting on that object, and the gravitational force cancelled that force and the total force should be zero.
But the problem is, there was no force acting on that thing upwards. The upward force acted when it was in our hand. As soon as it left the ground, all upward forces stopped acting and the object moved upward for its inertia. So gravitational force never cancelled anything, it was the only force acting there.
-g or g?? :|
Well, the position function was upward displacement, so $-g$ is the upward acceleration. That means $g$ is the downward acceleration.
"If people do not believe that mathematics is simple, it is only because they do not realize how complicated life is."
John von Neumann

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sakib17442
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Re: A Comeback Post (Assignment related)

Unread post by sakib17442 » Sun Jun 27, 2021 8:09 pm

Oops, sorry I misunderstood this and voted for 0. Please forgive me
Games You can't win because you'll play against yourself.
---Dr.Seuss

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