Question

Question 6.11 A body constrained to move along the z-axis of a coordinate system is subject to a constant force F given by

F= -i + 2j + 3k N

Where are i,j,k 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?

Chapter Work, Energy And Power Page 136

Answer 1

Hey there !!!!!

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Force applied on body = -i+2j+3k

With a displacement of 4m along z axis

s= 4k

Work done = F.s = (-i+2j+3k)(4k) = 12J


So work done by body when it moves 4m along z axis is 12Joules

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Hope this helped you.............................

Answer 2

Given,
F =( -i + 2j + 3k ) N
distance of 4m along z axis .
e.g S = 4k m

we know,
work done is the dot product of Force and displacement vectors .
e.g W = F.S
= ( -i + 2j + 3k).(4k )
= (-i + 2j + 3k)( 0i + 0j + 4k)
= -1×0 + 2×0 + 3×4
= 12 Joule

hence, work done = 12 Joule