Question

8.
A body constrained to move along the z-axis, under a constant force È.-1+2+3 N. Work done by this
force in moving the body a distance 4 m along the z-axis is
(1) 12 J
(2) 4J
(3) 23
(4) 6J

Answer 1

(1) 12J

Explanation:

Since the body is displaced 4m along the z-axis only,

S=0iˆ+0jˆ+4kˆ

Also, F=−i+2jˆ+3kˆ

Work done,

W=F→.S→=(−iˆ+2jˆ+3kˆ)⋅(0iˆ+jˆ+4kˆ)

=12(kˆ.kˆ)J=12J