• Support PF! Buy your school textbooks, materials and every day products via PF Here!

When is the particle speed up/slowing down

  • Thread starter betsinda
  • Start date
1. Homework Statement

The postion of a particle is given by s=2t^2-9t^2 where t is in seconds and s in meters

a) when is the particle speeding up/slowing down

2. Homework Equations



3. The Attempt at a Solution

I have calculated the
1st derivative (velocity) as 6t^2-18t
2nd derivative (acceleration) as 12t-18

and I know that the particle is speeding up when the velocity and the acceleration have the same sign and slowing down when they have opposite signs. However I am not sure how to express this to answer the question.

Thanks
1. Homework Statement



2. Homework Equations



3. The Attempt at a Solution
 
316
0
Find the values of t for which the velocity and for which the acceleration is positive/negative. Hint: They can only change sign at the zeros.
 

Related Threads for: When is the particle speed up/slowing down

Replies
1
Views
35K
Replies
15
Views
2K
  • Posted
Replies
1
Views
17K
  • Posted
Replies
1
Views
837

Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top