Three forces \(-63j , 32.14i + 38.3j\) and \(14i - 24.25j\) act on a body

FURTHER MATHEMATICS
WAEC 2012

Three forces \(-63j , 32.14i + 38.3j\) and \(14i - 24.25j\) act on a body of mass 5kg. Find, correct to one decimal place, the :

(a) magnitude of the resultant force ;

(b) acceleration of the body.

Explanation

(a) Resultant of forces, \(R = -63j + (32.14i + 38.3j) + (14i - 24.25j)\)

= \(46.14i - 48.95j\)

Magnitude |R| = \(\sqrt{(46.14)^{2} + (-48.95)^{2}}\)

= \(\sqrt{2128.9 + 2396.1}\)

= \(\sqrt{4525}\)

= \(67.268 \approxeq 67.3N\) (to 1 d.p)

(b) \(a = \frac{F}{m}\)

= \(\frac{67.268}{5} = 13.454 ms^{-2}\)

\(\approxeq 13.5 ms^{-2}\)



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