The position of a particle at the time t > 0 is represented by $s(t) = frac 13t^3- frac 72t^2+20t-10$ Announcing the arrival of Valued Associate #679: Cesar Manara Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)Position of a particle moving along the $x$-axis questionA particle moves on a horizontal line so that its coordinate at time $t$ is $x=ln(1+2t)-t^2+2, tgeq 0.$Higher Order Derivatives problem involving the position of a particleA particle moving in a straight line has an acceleration given by $a(t)=2t$. The initial velocity of the particle is $ 2 $ cm/sec.Calculate the average acceleration and average speed of a particleSpeeding Up and Slowing Down of ParticleA particle moves along the x-axis find t when acceleration of the particle equals 0A Particle Travelling in a Straight LineFind the velocity and position of the particle as function of t?A particles moves on a horizontal line so that its coordinate at time $t$ is $x = ln (1 + 2t) − t^2 + 2, t ≥ 0.$

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The position of a particle at the time t > 0 is represented by $s(t) = frac 13t^3- frac 72t^2+20t-10$



Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)Position of a particle moving along the $x$-axis questionA particle moves on a horizontal line so that its coordinate at time $t$ is $x=ln(1+2t)-t^2+2, tgeq 0.$Higher Order Derivatives problem involving the position of a particleA particle moving in a straight line has an acceleration given by $a(t)=2t$. The initial velocity of the particle is $ 2 $ cm/sec.Calculate the average acceleration and average speed of a particleSpeeding Up and Slowing Down of ParticleA particle moves along the x-axis find t when acceleration of the particle equals 0A Particle Travelling in a Straight LineFind the velocity and position of the particle as function of t?A particles moves on a horizontal line so that its coordinate at time $t$ is $x = ln (1 + 2t) − t^2 + 2, t ≥ 0.$










0












$begingroup$


At which time particle is speeding up?



From my experience I think velocity is calculated by taking first derivative s'(t), which is $s'(t)=t^2-7t+20$ and acceleration calculated by taking second derivative S''(t) which is $s''(t)=2t-7$.



How to find at which time it speeding up?










share|cite|improve this question











$endgroup$











  • $begingroup$
    Be careful with the "speeding up". In general, a particle with $s''(t_0)> 0$ is really "slowing down" at time $t_0$ if $s'(t_0) < 0$. (Because the speed is actually decreasing at this point!) If "speeding up" means the speed (not just velocity!) is increasing, you want the times $t$ such that $s''(t)$ and $s'(t)$ have the same sign, rather than just times where $s''(t) > 0$.
    $endgroup$
    – Minus One-Twelfth
    Apr 1 at 8:22
















0












$begingroup$


At which time particle is speeding up?



From my experience I think velocity is calculated by taking first derivative s'(t), which is $s'(t)=t^2-7t+20$ and acceleration calculated by taking second derivative S''(t) which is $s''(t)=2t-7$.



How to find at which time it speeding up?










share|cite|improve this question











$endgroup$











  • $begingroup$
    Be careful with the "speeding up". In general, a particle with $s''(t_0)> 0$ is really "slowing down" at time $t_0$ if $s'(t_0) < 0$. (Because the speed is actually decreasing at this point!) If "speeding up" means the speed (not just velocity!) is increasing, you want the times $t$ such that $s''(t)$ and $s'(t)$ have the same sign, rather than just times where $s''(t) > 0$.
    $endgroup$
    – Minus One-Twelfth
    Apr 1 at 8:22














0












0








0





$begingroup$


At which time particle is speeding up?



From my experience I think velocity is calculated by taking first derivative s'(t), which is $s'(t)=t^2-7t+20$ and acceleration calculated by taking second derivative S''(t) which is $s''(t)=2t-7$.



How to find at which time it speeding up?










share|cite|improve this question











$endgroup$




At which time particle is speeding up?



From my experience I think velocity is calculated by taking first derivative s'(t), which is $s'(t)=t^2-7t+20$ and acceleration calculated by taking second derivative S''(t) which is $s''(t)=2t-7$.



How to find at which time it speeding up?







calculus derivatives






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Apr 1 at 7:29







Aman Khan

















asked Apr 1 at 7:26









Aman KhanAman Khan

326




326











  • $begingroup$
    Be careful with the "speeding up". In general, a particle with $s''(t_0)> 0$ is really "slowing down" at time $t_0$ if $s'(t_0) < 0$. (Because the speed is actually decreasing at this point!) If "speeding up" means the speed (not just velocity!) is increasing, you want the times $t$ such that $s''(t)$ and $s'(t)$ have the same sign, rather than just times where $s''(t) > 0$.
    $endgroup$
    – Minus One-Twelfth
    Apr 1 at 8:22

















  • $begingroup$
    Be careful with the "speeding up". In general, a particle with $s''(t_0)> 0$ is really "slowing down" at time $t_0$ if $s'(t_0) < 0$. (Because the speed is actually decreasing at this point!) If "speeding up" means the speed (not just velocity!) is increasing, you want the times $t$ such that $s''(t)$ and $s'(t)$ have the same sign, rather than just times where $s''(t) > 0$.
    $endgroup$
    – Minus One-Twelfth
    Apr 1 at 8:22
















$begingroup$
Be careful with the "speeding up". In general, a particle with $s''(t_0)> 0$ is really "slowing down" at time $t_0$ if $s'(t_0) < 0$. (Because the speed is actually decreasing at this point!) If "speeding up" means the speed (not just velocity!) is increasing, you want the times $t$ such that $s''(t)$ and $s'(t)$ have the same sign, rather than just times where $s''(t) > 0$.
$endgroup$
– Minus One-Twelfth
Apr 1 at 8:22





$begingroup$
Be careful with the "speeding up". In general, a particle with $s''(t_0)> 0$ is really "slowing down" at time $t_0$ if $s'(t_0) < 0$. (Because the speed is actually decreasing at this point!) If "speeding up" means the speed (not just velocity!) is increasing, you want the times $t$ such that $s''(t)$ and $s'(t)$ have the same sign, rather than just times where $s''(t) > 0$.
$endgroup$
– Minus One-Twelfth
Apr 1 at 8:22











4 Answers
4






active

oldest

votes


















2












$begingroup$

$s''(t) >0$ if $t >frac 7 2$ so it is speending up for $t >frac 7 2$.






share|cite|improve this answer









$endgroup$




















    1












    $begingroup$

    If I understand correctly, "speeding up" refers to positive acceleration. Therefore, you want to find the second derivative of $s$, i.e. $s''(t)$, and find for which values of $t$ we have $s''(t) > 0$.



    This is best approached by considering the roots of the equation, and the behavior on other side of the roots. Since $s$ is a cubic, $s''$ will be linear, so one side of its root (of which there is only one) it will be negative (slowing down) and on the other $s''$ will be positive (speeding up).



    Determine that and you will have an infinite interval, from that root, to the corresponding infinity, on which the particle speeds up.






    share|cite|improve this answer









    $endgroup$




















      1












      $begingroup$

      "speed" does not have direction; velocity does.



      $textvelocity = s'\
      text speed = |s'|$



      $s' = t^2 - 7t + 20$



      $s' > 0 $ for all $t.$



      That makes things easier. Then we only need to know when $s'' > 0$



      $s'' = 2t - 7 > 0\
      t > frac 72$






      share|cite|improve this answer









      $endgroup$












      • $begingroup$
        Problem specifically mentions "speeding up", which means increase of speed or acceleration.
        $endgroup$
        – Aman Khan
        Apr 1 at 8:22










      • $begingroup$
        If you are traveling to the right, and your acceleration is positive, you are speeding up. If you are traveling to the left, and your acceleration is positive, you are slowing down. If you are traveling to the left and your acceleration is negative, you are slowing down.
        $endgroup$
        – Doug M
        Apr 2 at 18:19


















      1












      $begingroup$

      Equate this equation to $zero $ to find the time it starts speeding up in other words"accelarating"
      $s′′(t)=2t−7$
      $2t−7=0$
      $2t=7$
      $t=frac 72$ , that's the time it speeds up.






      share|cite|improve this answer









      $endgroup$













        Your Answer








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        4 Answers
        4






        active

        oldest

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        4 Answers
        4






        active

        oldest

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        active

        oldest

        votes






        active

        oldest

        votes









        2












        $begingroup$

        $s''(t) >0$ if $t >frac 7 2$ so it is speending up for $t >frac 7 2$.






        share|cite|improve this answer









        $endgroup$

















          2












          $begingroup$

          $s''(t) >0$ if $t >frac 7 2$ so it is speending up for $t >frac 7 2$.






          share|cite|improve this answer









          $endgroup$















            2












            2








            2





            $begingroup$

            $s''(t) >0$ if $t >frac 7 2$ so it is speending up for $t >frac 7 2$.






            share|cite|improve this answer









            $endgroup$



            $s''(t) >0$ if $t >frac 7 2$ so it is speending up for $t >frac 7 2$.







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered Apr 1 at 7:29









            Kavi Rama MurthyKavi Rama Murthy

            75.3k53270




            75.3k53270





















                1












                $begingroup$

                If I understand correctly, "speeding up" refers to positive acceleration. Therefore, you want to find the second derivative of $s$, i.e. $s''(t)$, and find for which values of $t$ we have $s''(t) > 0$.



                This is best approached by considering the roots of the equation, and the behavior on other side of the roots. Since $s$ is a cubic, $s''$ will be linear, so one side of its root (of which there is only one) it will be negative (slowing down) and on the other $s''$ will be positive (speeding up).



                Determine that and you will have an infinite interval, from that root, to the corresponding infinity, on which the particle speeds up.






                share|cite|improve this answer









                $endgroup$

















                  1












                  $begingroup$

                  If I understand correctly, "speeding up" refers to positive acceleration. Therefore, you want to find the second derivative of $s$, i.e. $s''(t)$, and find for which values of $t$ we have $s''(t) > 0$.



                  This is best approached by considering the roots of the equation, and the behavior on other side of the roots. Since $s$ is a cubic, $s''$ will be linear, so one side of its root (of which there is only one) it will be negative (slowing down) and on the other $s''$ will be positive (speeding up).



                  Determine that and you will have an infinite interval, from that root, to the corresponding infinity, on which the particle speeds up.






                  share|cite|improve this answer









                  $endgroup$















                    1












                    1








                    1





                    $begingroup$

                    If I understand correctly, "speeding up" refers to positive acceleration. Therefore, you want to find the second derivative of $s$, i.e. $s''(t)$, and find for which values of $t$ we have $s''(t) > 0$.



                    This is best approached by considering the roots of the equation, and the behavior on other side of the roots. Since $s$ is a cubic, $s''$ will be linear, so one side of its root (of which there is only one) it will be negative (slowing down) and on the other $s''$ will be positive (speeding up).



                    Determine that and you will have an infinite interval, from that root, to the corresponding infinity, on which the particle speeds up.






                    share|cite|improve this answer









                    $endgroup$



                    If I understand correctly, "speeding up" refers to positive acceleration. Therefore, you want to find the second derivative of $s$, i.e. $s''(t)$, and find for which values of $t$ we have $s''(t) > 0$.



                    This is best approached by considering the roots of the equation, and the behavior on other side of the roots. Since $s$ is a cubic, $s''$ will be linear, so one side of its root (of which there is only one) it will be negative (slowing down) and on the other $s''$ will be positive (speeding up).



                    Determine that and you will have an infinite interval, from that root, to the corresponding infinity, on which the particle speeds up.







                    share|cite|improve this answer












                    share|cite|improve this answer



                    share|cite|improve this answer










                    answered Apr 1 at 7:31









                    Eevee TrainerEevee Trainer

                    10.5k31842




                    10.5k31842





















                        1












                        $begingroup$

                        "speed" does not have direction; velocity does.



                        $textvelocity = s'\
                        text speed = |s'|$



                        $s' = t^2 - 7t + 20$



                        $s' > 0 $ for all $t.$



                        That makes things easier. Then we only need to know when $s'' > 0$



                        $s'' = 2t - 7 > 0\
                        t > frac 72$






                        share|cite|improve this answer









                        $endgroup$












                        • $begingroup$
                          Problem specifically mentions "speeding up", which means increase of speed or acceleration.
                          $endgroup$
                          – Aman Khan
                          Apr 1 at 8:22










                        • $begingroup$
                          If you are traveling to the right, and your acceleration is positive, you are speeding up. If you are traveling to the left, and your acceleration is positive, you are slowing down. If you are traveling to the left and your acceleration is negative, you are slowing down.
                          $endgroup$
                          – Doug M
                          Apr 2 at 18:19















                        1












                        $begingroup$

                        "speed" does not have direction; velocity does.



                        $textvelocity = s'\
                        text speed = |s'|$



                        $s' = t^2 - 7t + 20$



                        $s' > 0 $ for all $t.$



                        That makes things easier. Then we only need to know when $s'' > 0$



                        $s'' = 2t - 7 > 0\
                        t > frac 72$






                        share|cite|improve this answer









                        $endgroup$












                        • $begingroup$
                          Problem specifically mentions "speeding up", which means increase of speed or acceleration.
                          $endgroup$
                          – Aman Khan
                          Apr 1 at 8:22










                        • $begingroup$
                          If you are traveling to the right, and your acceleration is positive, you are speeding up. If you are traveling to the left, and your acceleration is positive, you are slowing down. If you are traveling to the left and your acceleration is negative, you are slowing down.
                          $endgroup$
                          – Doug M
                          Apr 2 at 18:19













                        1












                        1








                        1





                        $begingroup$

                        "speed" does not have direction; velocity does.



                        $textvelocity = s'\
                        text speed = |s'|$



                        $s' = t^2 - 7t + 20$



                        $s' > 0 $ for all $t.$



                        That makes things easier. Then we only need to know when $s'' > 0$



                        $s'' = 2t - 7 > 0\
                        t > frac 72$






                        share|cite|improve this answer









                        $endgroup$



                        "speed" does not have direction; velocity does.



                        $textvelocity = s'\
                        text speed = |s'|$



                        $s' = t^2 - 7t + 20$



                        $s' > 0 $ for all $t.$



                        That makes things easier. Then we only need to know when $s'' > 0$



                        $s'' = 2t - 7 > 0\
                        t > frac 72$







                        share|cite|improve this answer












                        share|cite|improve this answer



                        share|cite|improve this answer










                        answered Apr 1 at 7:35









                        Doug MDoug M

                        1,996412




                        1,996412











                        • $begingroup$
                          Problem specifically mentions "speeding up", which means increase of speed or acceleration.
                          $endgroup$
                          – Aman Khan
                          Apr 1 at 8:22










                        • $begingroup$
                          If you are traveling to the right, and your acceleration is positive, you are speeding up. If you are traveling to the left, and your acceleration is positive, you are slowing down. If you are traveling to the left and your acceleration is negative, you are slowing down.
                          $endgroup$
                          – Doug M
                          Apr 2 at 18:19
















                        • $begingroup$
                          Problem specifically mentions "speeding up", which means increase of speed or acceleration.
                          $endgroup$
                          – Aman Khan
                          Apr 1 at 8:22










                        • $begingroup$
                          If you are traveling to the right, and your acceleration is positive, you are speeding up. If you are traveling to the left, and your acceleration is positive, you are slowing down. If you are traveling to the left and your acceleration is negative, you are slowing down.
                          $endgroup$
                          – Doug M
                          Apr 2 at 18:19















                        $begingroup$
                        Problem specifically mentions "speeding up", which means increase of speed or acceleration.
                        $endgroup$
                        – Aman Khan
                        Apr 1 at 8:22




                        $begingroup$
                        Problem specifically mentions "speeding up", which means increase of speed or acceleration.
                        $endgroup$
                        – Aman Khan
                        Apr 1 at 8:22












                        $begingroup$
                        If you are traveling to the right, and your acceleration is positive, you are speeding up. If you are traveling to the left, and your acceleration is positive, you are slowing down. If you are traveling to the left and your acceleration is negative, you are slowing down.
                        $endgroup$
                        – Doug M
                        Apr 2 at 18:19




                        $begingroup$
                        If you are traveling to the right, and your acceleration is positive, you are speeding up. If you are traveling to the left, and your acceleration is positive, you are slowing down. If you are traveling to the left and your acceleration is negative, you are slowing down.
                        $endgroup$
                        – Doug M
                        Apr 2 at 18:19











                        1












                        $begingroup$

                        Equate this equation to $zero $ to find the time it starts speeding up in other words"accelarating"
                        $s′′(t)=2t−7$
                        $2t−7=0$
                        $2t=7$
                        $t=frac 72$ , that's the time it speeds up.






                        share|cite|improve this answer









                        $endgroup$

















                          1












                          $begingroup$

                          Equate this equation to $zero $ to find the time it starts speeding up in other words"accelarating"
                          $s′′(t)=2t−7$
                          $2t−7=0$
                          $2t=7$
                          $t=frac 72$ , that's the time it speeds up.






                          share|cite|improve this answer









                          $endgroup$















                            1












                            1








                            1





                            $begingroup$

                            Equate this equation to $zero $ to find the time it starts speeding up in other words"accelarating"
                            $s′′(t)=2t−7$
                            $2t−7=0$
                            $2t=7$
                            $t=frac 72$ , that's the time it speeds up.






                            share|cite|improve this answer









                            $endgroup$



                            Equate this equation to $zero $ to find the time it starts speeding up in other words"accelarating"
                            $s′′(t)=2t−7$
                            $2t−7=0$
                            $2t=7$
                            $t=frac 72$ , that's the time it speeds up.







                            share|cite|improve this answer












                            share|cite|improve this answer



                            share|cite|improve this answer










                            answered Apr 1 at 7:39









                            Yasir MKYasir MK

                            114




                            114



























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