Finding the speed of a book against a vertical wall

Click For Summary

Homework Help Overview

The problem involves determining the speed of a book after it has traveled a certain distance up a vertical wall, starting from rest. The context includes analyzing forces acting on the book, including friction and gravitational forces, using free body diagrams and kinematic equations.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the setup of free body diagrams and the equations derived from them. There is a question regarding the direction of the frictional force and its role in the equations. Some participants express uncertainty about the correct application of kinematic equations after determining acceleration.

Discussion Status

The discussion is ongoing with participants clarifying their understanding of the forces involved and the implications of the problem statement. Some guidance has been offered regarding the use of kinematic equations once acceleration is determined, but there is no explicit consensus on the final approach yet.

Contextual Notes

Participants are working under the assumption that the book is moving upward, which influences their analysis of forces and the direction of friction. There is a mention of needing to account for gravitational force in their equations.

Vanessa Avila
Messages
94
Reaction score
1

Homework Statement



t09diQz.jpg

the main question asks: "If the book is initially at rest, what is its speed after it has traveled 0.400 m up the wall?"

Homework Equations


∑F = m*a
vf2 = vi2 + 2 * a * d , when initial velocity is 0.

The Attempt at a Solution


So here's my free body diagram:
kOUypje.jpg

and out of that FBD I got these equations:
∑Fx=N−Fcos(60)=0
∑Fy=fk+Fsin(60)=ma

I know that fk=μ(Fcos(60)) = μN

Should i solve for the acceleration and then plug it in the kinematics equation to solve for final velocity? And are my equations and FBD right?
 
Physics news on Phys.org
Vanessa Avila said:

Homework Statement



t09diQz.jpg

the main question asks: "If the book is initially at rest, what is its speed after it has traveled 0.400 m up the wall?"

Homework Equations


∑F = m*a
vf2 = vi2 + 2 * a * d , when initial velocity is 0.

The Attempt at a Solution


So here's my free body diagram:
kOUypje.jpg

and out of that FBD I got these equations:
∑Fx=N−Fcos(60)=0
∑Fy=fk+Fsin(60)=ma

I know that fk=μ(Fcos(60)) = μN

Should i solve for the acceleration and then plug it in the kinematics equation to solve for final velocity? And are my equations and FBD right?
The book is moving upward. Shouldn't the frictional force be downward then?
 
cnh1995 said:
The book is moving upward. Shouldn't the frictional force be downward then?
Oh okay so Fsin60 - mg - fk then? I forgot to add the mg on my equation up there.
 
Vanessa Avila said:
Oh okay so Fsin60 - mg - fk then
Right.
 
cnh1995 said:
Right.
Ohh okay i didn't catch the "up" part on the question. So i can solve for acceleration now then given that equation?
 
Vanessa Avila said:
Ohh okay i didn't catch the "up" part on the question. So i can solve for acceleration now then given that equation?
Yes. And then plug it in the kinematic equation
Vanessa Avila said:
vf2 = vi2 + 2 * a * d
 
cnh1995 said:
Yes. And then plug it in the kinematic equation
Awesome. I did that and i got the right answer. Thanks a lot! :)
 
  • Like
Likes   Reactions: cnh1995

Similar threads

  • · Replies 7 ·
Replies
7
Views
5K
  • · Replies 21 ·
Replies
21
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 16 ·
Replies
16
Views
7K
Replies
4
Views
3K
  • · Replies 8 ·
Replies
8
Views
2K
Replies
6
Views
13K
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K