Question

The forces F 1, F 2, ..., F n acting at the same point P are said to be in equilibrium if the resultant force is zero, that is, if F 1 + F 2 + ... + F n = 0.



F 1 = i + j, F 2 = i – j, F 3 = 9 i + 2 j

Find the additional force required for the forces to be in equilibrium P.

Answer 1

do the same as we did
F1 =<1, 1> in this case, consider F1 as u = <u1,u2>=<1,1>
F2= <1,-1> F2 as v = <v1,v2>= <1,-1>
F3= <9,2> F3 as w =<w1,w2>=<9,2>
so you need
F4 = <x, y>
such that x + u1+v1+w1 =0 or x = -u1-v1-w1
do the same with y
combine them to get F4

Answer 2

so F4 = <11,2>?

Answer 3

<-11,-2>
be careful with the signs

Answer 4

??? x = u1+v1+w1 ? therefore 1+1+9 = 11 ?

Answer 5

re read, I said x + u1+ v1 + w1 =0 or x = - u1 -v1-w1 = -1-1-9 =-11

Answer 6

if x + u1 + v1 + w1 it will become 0?

Answer 7

is it bcoz x has not value ?

Answer 8

think of this situation,
you apply a force to the right
your girlfriend applies a force to the right
your closed friend applies a force to the right
I want to balance the force, so I must applies a force TO THE LEFT
right? and the magnitude of my force must be = the sum of you guys, right?

Answer 9

ahhhhh !! i got it ..

Answer 10

good for you, hehehe

Answer 11

so its -11,-2 ?

Answer 12

yup

Answer 13

oh come on !! youre my hero !! youre a lifesaver ^^

Answer 14

ty