Question

8. two forces of magnitude 8N and15N respectively act at a point. If the resultant force is 17 N , the angle between the forces has to be
1) 60 degree
2) 45 degree
3)90 degree
4)30 degree

Q. Two forces of 10N and 16N act upon a body. The direction of the forces are unknown. The resultant force on the body may be
1) 15N
2)3N
3)17N
4)2N


need step by step explanation


Q. the vector OA where O is origin is given by a is equals to two 2^i + 2^j . now it is rotated by 45 degree anticlockwise about O. what will be the new vector?

1) 2√2
2)2^j
3)2^i
4)2√2^i

please guys answer this if you can do one question so please answer

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Answer 1

1----- 3.)

2-----2.)

3-----4.)

Answer 2

Answer:

1.The equation to use here is the triangular law of vector addition.

 

F = a²+b²+2abcosθ

Given a = 8 N

           b = 15 N

           F = 17 N

we need to find the value of θ

if we put all values in the above equation, we get

17²= 8²+15²+2.8.15.cosθ

289= 64+ 225+ 240cosθ

240cosθ= 0

cosθ= 0

θ= 90°answer

then option(3)

2. The resultant of two vectors A and B should always lie between (A+B) and (A-B)

Thus the resultant should lie between 16N and 4N.

So, the resultant should be any in between these values. I think

15n is your answer

then option(1)

3.Let OA=a

x component is j^

cosθ=a.b/|a| |b|

cosθ=2/2√2

cosθ=1/√2

θ=45°

angle rotated through 45° anti clockwise

then new angle will be 45+45=90°

x component will be zero

y component will be 2√2i^

the new vector is 2√2i^

then option(4)

I hope all answer are help u

and correct