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Question
A body constrained to move along the z-axis of a coordinate system is subject to a constant force F given by
`F = -hati+2hatj+3hatkN`
Where `hati,hatj,hatk` are unit vectors along the x-, y- and z-axis of the system respectively. What is the work done by this force in moving the body a distance of 4 m along the z-axis ?
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Solution
Since the body is displaced 4m among z-axis only.
`:. hatS = 0hati +0hatj+4hatk`
Also `vecF = -hati +2hatj + 3hatk`
Work Done, `W = vecF.vecS`
`= (-hati+2hatj+3hatk).(0hati+0hatj+4hatk)`
`= 12 (hatk.hatk)` joule = 12 Joule
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