Question

Work done by the force F = (3i – 2j+4K)N in
displacing an object of mass 2 kg from point
P(-1, 2, 3) m to a point Q (2,-1,0) m, will be
(1) 3J
(2) 6J
(3) 9 J
(4) -3J​

Answer 1

option 2) 6 j is correct

$\huge \red{ \mathfrak{solution}}$

Given:

force = 3i-2j+4k

and

mass= 2 kg

Displacement = Q-P

=> 2i-j-(-i+2j+3k)

=> 3i-3j-3k

As we know that :

$\blue{\boxed{ \green{ \: work = (force)(displacement)}}}$

=> (3i-2j+4k)(3i-3j-3k)

=> 3 J

And mass is 2kg which is displaced ,

so

w= 3×2

w= 6 J

soln refers to the attachment

Answer 2

Here:-

Displacement= Q-P

so

Q=(2I, -1J,0K)

P=(-1I, 2 J, 3K)

D=(3I, -3J,-3K)×2

Now

Work done= F×D

= (3I-2J+4K)×(6I-6J-6K)

= 18+12-24

= 18-12

=6J