Is my teacher wrong? Problem dealing with forces.

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The discussion revolves around a physics problem involving forces, where the student initially calculated the net force incorrectly as 32N, while the teacher stated it was 77.5N. The student misunderstood the direction of forces, particularly with Fnety, believing it should be -25N due to opposing forces. Clarification revealed that Fnety should be calculated as 25N = Fy - 50N, leading to the correct understanding of the problem. The importance of correctly applying signs to forces was emphasized for accurate calculations.
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Homework Statement


Problem is in the picture


Homework Equations


The teacher told us the
Fnetx = 20N - Fx (Fx is 0)
Fnety = Fy - 50N (Fy = +25N)


The Attempt at a Solution


My answer was 32N. But my teacher said the answer was C. which was 77.5N. He got it because Fnety = 75N for him. But that to me doesn't make sense since the Fy and 50N are pointing in opposite directions, won't Fnety be = -25N?
 

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Oh nvm i think i got it. I think he meant to put that:
25N = Fy - 50 huh? Darn and to think i could prove a teacher wrong ;"D
 
Welcome to PF.
Kinermatics said:
Oh nvm i think i got it. I think he meant to put that:
25N = Fy - 50 huh? Darn and to think i could prove a teacher wrong ;"D
Glad it worked out finally. The key here was to think carefully about which sign (+ or -) goes with each force -- including Fnety, which we know is + because the object accelerates in the +y direction.
The teacher told us the
Fnetx = 20N - Fx (Fx is 0)
Fnety = Fy - 50N (Fy = +25N)
It pays to be careful -- those forces in parentheses should read (Fnetx is 0) and (Fnety = +25N)
 

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