Question

Alternative Exercise 4.61:

Constants Two forces have the same magnitude F

Need Part A, Part B, and Part C

Answer 1

Let A be the vector having magnitude F

B be the vector having magnitude F

Now by the vector law

$(A+B)^2=A^2+B^2+2*A*B*cos\Theta$ ................(1)

Now in part b

Sum of both vectors is 2F

A+B=2F

(1)->  $(2F)^2=F^2+F^2+2*F*F*cos\Theta$

$4=2+2cos\Theta$

$2=1+cos\Theta$

$cos\Theta =1$

$\Theta =0$

Hence the Angle between two vector is 0

For part c

Now sum of both vectors is 0

A+B=0

$(A+B)^2=A^2+B^2+2*A*B*cos\Theta$

$0=F^2+F^2+2*F*F*cos\Theta$

$0=2+2cos\Theta$

$0=1+cos\Theta$

$cos\Theta =-1$

$\Theta =$180°

Is answer