Velocity of an Object given its position as a function of time

[Strand9202]

Homework Statement

Velocity of an object: Picture of problem and work attached

Relevant Equations

Speed =s(t)
Acceleration = s'(t)
Velocity = s"(t) or a'(t)

Attached is the problem and my work through the problem. I got the problem correct, but my teacher said this could be done quicker on a calculator. Any idea how it could be done quicker.

 

[FactChecker]

Check your relevant equations.
In #6, s(t) is the position, not the speed (an unfortunate choice of variables).
Speed is the derivative of position
Acceleration is the derivative of speed.

 

[Strand9202]

Check your relevant equations.
In #6, s(t) is the position, not the speed (an unfortunate choice of variables).
Speed is the derivative of position
Acceleration is the derivative of speed.

My work for number 6 is correct. My teacher checked it, but they said I could have used a calculator to find it quicker.

 

[FactChecker]

Sorry, I missed that your work was correct. In any case, I stopped reading when I saw that your "Relevant Equations" are all wrong.
Do you have a graphing calculator? Maybe your teacher means that you can look at the graph of position and determine the answer.

 

[Mark44]

I got the problem correct, but my teacher said this could be done quicker on a calculator.

Well, lots of things can be done more quickly on a calculator, but so what? If I were the teacher, and I've taught many calculus classes, I would be happy with your work.
As a PF member, I'm not quite as happy, since your images are all rotated by 90°. Your handwriting is very clear, though, and the images are well-lit.

 

[Strand9202]

Well, lots of things can be done more quickly on a calculator, but so what? If I were the teacher, and I've taught many calculus classes, I would be happy with your work.
As a PF member, I'm not quite as happy, since your images are all rotated by 90°. Your handwriting is very clear, though, and the images are well-lit.

Sorry I thought I put the right side pictures up. I reedited and attached the correct ones.