Lifting Books - Potential Energy

Click For Summary
SUMMARY

The discussion focuses on calculating the minimum work required to stack six books, each weighing 30N and having a thickness of 4cm, from a table. The relevant equations include potential energy (Ep = mgh) and kinetic energy (Ec = (mv²)/2). The mass of each book is determined to be 3.06kg, and the gravitational acceleration is 9.81 m/s². The key insight is that the work done increases with the height each book is lifted, necessitating a careful calculation of the cumulative height for each book in the stack.

PREREQUISITES
  • Understanding of potential energy and work (Ep = mgh)
  • Basic knowledge of gravitational force (9.81 m/s²)
  • Ability to convert units (cm to m)
  • Familiarity with the concept of constant speed in physics
NEXT STEPS
  • Calculate the total work done to stack the six books using the formula W = F * d.
  • Explore the implications of lifting objects at constant speed on work done.
  • Investigate the relationship between mass, height, and work in physics problems.
  • Review examples of potential energy calculations in similar scenarios.
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and energy concepts, as well as educators looking for practical examples of work and energy calculations.

Ipos Manger
Messages
31
Reaction score
0

Homework Statement


A student has six books, all of them with a 4cm thickness and a weight of 30N. ¿What would be the minimum work to put the books in one pile, if the six books are in a table?

Weight: 30N
Thickness: 4cm.
Gravity: 9.81ms-2

Homework Equations



Ep=mgh

Ec=(mv2)/2

The Attempt at a Solution



I found the mass of each book, which is 3.06kg, and converted the thickness to m, 0.04m.

After that, I'm lost. :S I don't know how to work it out..
 
Physics news on Phys.org
You need to find the amount of work it takes to put one book on top of another book! You know that the work needed to move one book onto the other one is:

(the mass of the book) * (the acceleration due to gravity) * (the height the book must be lifted).

Think about what the height will be that you must lift each book (HINT: it's a number that will increase for each book you stack onto your stack!)
 
Ipos Manger said:

Homework Statement


A student has six books, all of them with a 4cm thickness and a weight of 30N. ¿What would be the minimum work to put the books in one pile, if the six books are in a table?

Weight: 30N
Thickness: 4cm.
Gravity: 9.81ms-2

Homework Equations



Ep=mgh

Ec=(mv2)/2

The Attempt at a Solution



I found the mass of each book, which is 3.06kg, and converted the thickness to m, 0.04m.

After that, I'm lost. :S I don't know how to work it out..
Your relevant equations talk about potential and kinetic energy, but I think you are looking for the minimum work done by the student (not the total work done, although the problem is not worded clearly that way). Minimum work ocurs when the books are moved slowly at constant speed. What equations do you know for work done at constant speed?
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 4 ·
Replies
4
Views
2K
Replies
7
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 11 ·
Replies
11
Views
6K
  • · Replies 1 ·
Replies
1
Views
2K