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

Reflex action

  • Thread starter ritwik06
  • Start date
580
0
arvind drops a scale vertically which is grabbed by Vijay whose hand is just below the scale. In the mean time the scale slips by 20cm. What is the reflex time of Vijay?
 

cristo

Staff Emeritus
Science Advisor
8,056
72
Do you know any equations that may help you here? (hint: constant acceleration).

Is there a reason why this is in the tutorial forum? In future please post in the homework forum.
 
580
0
Do you know any equations that may help you here? (hint: constant acceleration).

Is there a reason why this is in the tutorial forum? In future please post in the homework forum.
yes, the acceleration will be 9.8 m/sec^2. But how will this help?

oh! I am sorry once again. I havent understood till now, as to which question should I post in which section. I am sorry again.
 

cristo

Staff Emeritus
Science Advisor
8,056
72
yes, the acceleration will be 9.8 m/sec^2. But how will this help?
Correct. Do you know any equations that will help you here? You are told the displacement, and you know that the initial velocity is zero.

oh! I am sorry once again. I havent understood till now, as to which question should I post in which section. I am sorry again.
That's ok. I'm sure it'll be moved for you soon anyway! In future though, use the homework forum. It's the second forum in the list on the front page (just under the tutorial forum)
 
580
0
Correct. Do you know any equations that will help you here? You are told the displacement, and you know that the initial velocity is zero.



That's ok. I'm sure it'll be moved for you soon anyway! In future though, use the homework forum. It's the second forum in the list on the front page (just under the tutorial forum)
Nope which equation are you talking about?

Ok! I will use the homework section. Thanks!

sorry once again.
 

cristo

Staff Emeritus
Science Advisor
8,056
72
Have you come across the kinematic equations, for constant acceleration? Here's a link to them (scroll about half way down the page): http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/1DKin/U1L6a.html [Broken]. Which one do you think is most useful in this case?
 
Last edited by a moderator:
580
0
Have you come across the kinematic equations, for constant acceleration? Here's a link to them (scroll about half way down the page): http://www.glenbrook.k12.il.us/GBSSCI/PHYS/Class/1DKin/U1L6a.html [Broken]. Which one do you think is most useful in this case?
will the 3rd one help? I have not studdied kinematics yet :S
 
Last edited by a moderator:

cristo

Staff Emeritus
Science Advisor
8,056
72
will the 3rd one help? I have not studdied kinematics yet :S
Ok, well you should use the first equation:[tex]d=v_it+\frac{1}{2}at^2[/tex]. Here, note that vi=0, so this simplifies the equation somewhat. a is the acceleration due the gravity (9.81), d is the distance measured on the ruler, and t is the reaction time that you require.
 
Last edited:

Related Threads for: Reflex action

  • Posted
Replies
3
Views
2K
  • Posted
Replies
5
Views
502
  • Posted
Replies
14
Views
2K
  • Posted
Replies
1
Views
951
  • Posted
Replies
5
Views
831
  • Posted
Replies
3
Views
6K
  • Posted
Replies
18
Views
3K
  • Posted
Replies
6
Views
2K

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