Adding vectors

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Homework Statement



Three movers are applying forces F1 = 100 N [W20°N], F2 = 200 N [E40°S], and F3 = 300 N on a 300-kg grand piano. If μK for the piano is 0.10, determine
a) the net force acting on the piano
b) the acceleration of the piano

The Attempt at a Solution



34rap83.png


I got an answer of 395 N going down and 276.9 going left.

Fnet = 482.38N

But the answer sheet says 106N

:(

Help please.
 

Answers and Replies

  • #2
SammyS
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Homework Statement



Three movers are applying forces F1 = 100 N [W20°N], F2 = 200 N [E40°S], and F3 = 300 N on a 300-kg grand piano. If μK for the piano is 0.10, determine
a) the net force acting on the piano
b) the acceleration of the piano

The Attempt at a Solution



34rap83.png


I got an answer of 395 N going down and 276.9 going left. (Actually is East, not left.)

Fnet = 482.38N

But the answer sheet says 106N

:(

Help please.

How in the world do you get 276.9 N going left?
 
  • #3
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How in the world do you get 276.9 N going left?
I subtracted the amount of force going right from the friction. Is that wrong?
 
  • #4
Nugatory
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I subtracted the amount of force going right from the friction. Is that wrong?
In which direction does the friction force act?
 
  • #5
SammyS
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I subtracted the amount of force going right from the friction. Is that wrong?
That's wrong.

These are compass directions.

The positive y direction is North, not up, etc.

Gravity acts in the direction into the page. The normal force is out of the page.


Find the resultant force for the three given forces. Assuming that the direction of motion is in the direction of the acceleration, you can then account for the direction in which the friction force acts.
 

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