MHB The work energy principle and power

AI Thread 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.
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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!
 
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