Question

Hello guys! Please solve question 17 and 18.

Answer 1

18) (4) 19) (4)

R^2 = A^2 + B^2 + 2ABcos@

(A^2 + B^2) = |A+B|^2 + |A-B|^2 + 2|A+B||A-B|cos@

(A^2 + B^2) = 2|A^2 + B^2| + 2|A^2 - B^2|cos@

- [(A^2 + B^2)]/2 = |A^2 - B^2|cos@

cos@ = - [(A^2 + B^2)]/2|A^2 - B^2|

cos@ = [(A^2 + B^2)]/2|B^2 - A^2]

@ = cos^(1)[A^2 + B^2)]/2|B^2 - A^2]

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length :L : L' = L/2

velocity v : L'T'^-1 = (LT^-1)/2; v' = (L/2)(T/2)^-1 hence T' = T/2

Force : MLT^-2 = (MLT^-2 )/2 ; F' = (M/2) (L/2)(T/2)^-1 ; hence M' = M/2

now....Power :P = ML^2T^-3

P' : M'L'^2T'^-3

= (M/2)(L/2)^2(T/2)^-3 =

= ML^2T^-3 /(2× 4 /8) = ML^2T^-3 (8/8)

P' = ML^2T^-3 = P

therefore , no change in power units

remains unchanged