MHB The work energy principle and power

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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.
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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
 
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$W_{net} = [22\cos(40) - 12]\cdot 5 = \dfrac{1}{2} \cdot 25 \cdot v_f^2 \implies v_f = 1.39 \, m/s$
 
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!
 
Here is a little puzzle from the book 100 Geometric Games by Pierre Berloquin. The side of a small square is one meter long and the side of a larger square one and a half meters long. One vertex of the large square is at the center of the small square. The side of the large square cuts two sides of the small square into one- third parts and two-thirds parts. What is the area where the squares overlap?

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