MHB The work energy principle and power

Click For Summary
The discussion centers on calculating the final speed of a 25kg box pulled 5m across a smooth floor with a tension of 22N at a 40-degree angle and an average frictional force of 12N. The net work done on the box is calculated using the formula W_net = [22cos(40) - 12] * 5, leading to the conclusion that the final speed should be 1.39 m/s. This result aligns with the textbook answer, contrasting with an initial calculation of 1.97 m/s. The correct application of the work-energy principle is emphasized in determining the final speed. The accurate final speed is confirmed to be 1.39 m/s.
Shah 72
MHB
Messages
274
Reaction score
0
A box of mass 25kg is pulled 5m across a smooth floor by rope with tension 22N. The rope is inclined at 40 degree to above the horizontal. There is a frictional force with average value 12N. The box starts from rest. Find the final speed.
Iam getting the ans 1.97m/s.
The textbook ans is 1.39 m/s
Pls help
 
Mathematics news on Phys.org
$W_{net} = [22\cos(40) - 12]\cdot 5 = \dfrac{1}{2} \cdot 25 \cdot v_f^2 \implies v_f = 1.39 \, m/s$
 
skeeter said:
$W_{net} = [22\cos(40) - 12]\cdot 5 = \dfrac{1}{2} \cdot 25 \cdot v_f^2 \implies v_f = 1.39 \, m/s$
Thank you!
 
Thread 'Erroneously  finding discrepancy in transpose rule'
Obviously, there is something elementary I am missing here. To form the transpose of a matrix, one exchanges rows and columns, so the transpose of a scalar, considered as (or isomorphic to) a one-entry matrix, should stay the same, including if the scalar is a complex number. On the other hand, in the isomorphism between the complex plane and the real plane, a complex number a+bi corresponds to a matrix in the real plane; taking the transpose we get which then corresponds to a-bi...

Similar threads

  • · Replies 1 ·
Replies
1
Views
888
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 16 ·
Replies
16
Views
2K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 4 ·
Replies
4
Views
1K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 17 ·
Replies
17
Views
1K
  • · Replies 9 ·
Replies
9
Views
1K
  • · Replies 9 ·
Replies
9
Views
2K