Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

catsrule332

  • 2 years ago

A 25 kg block is at rest on a horizontal surface. A horizontal force of 75 N is required to set the block in motion. When it is in motion a 60 N forced is required to keep the block moving with a constant speed. Find the coefficients of static and kinetic friction. Draw a force diagram and explain!

  • This Question is Closed
  1. salini
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    so catsrule wat have u figured out so far in this question?

  2. catsrule332
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    find normal force: n=mg=(25)(9.8)= 245 N \[f=m*\eta\]|dw:1333113193720:dw|

  3. JamesJ
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    When the object is not moving, the maximum frictional force on the block is the static friction. Static friction is given by \[ Fr_S = \mu_S N \] where \( \mu_S \) is the coefficient of static friction. Now which force in the problem is that equal to?

  4. salini
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    u are in the right track wat is the expression for frictional force with normal reaction? and do u know the difference abt co-efficient of static friction and kinetic friction?

  5. JamesJ
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    On the other hand, once the object is moving, the maximum frictional force is the kinetic friction and that is given by \[ Fr_K = \mu_K N \] where \( \mu_K \) is the coefficient of kinetic friction and of course \( N \) is the normal force. What value is the kinetic friction equal to in this problem?

  6. salini
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    cats rule james has given everything needed for the sum u have to get the answer using that

  7. catsrule332
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 0

    Static friction: fsmax=\[\mu *\eta\] Kinetic friction: fk=\[\mu * \eta\] 75/(25)(9.8)= .31 N 60/245) =.24 N

  8. JamesJ
    • 2 years ago
    Best Response
    You've already chosen the best response.
    Medals 2

    Yes, the coefficient of static friction is 0.31. Notice that these coefficients are unitless, because you have Newtons on both sides of the equation \( F = \mu N \) and force of friction \( F \) and the normal force \( F \) both have units of Newtons.

  9. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.