Question

F= 4i+6j+3k
S=2i+3j+5k
Find work done

Answer 1

I should take the dot-product or vector product

Answer 2

yes

Answer 3

what?

Answer 4

you are correct, take the dot product

Answer 5

why?

Answer 6

why not vector product

Answer 7

oh i didn't read whatyou had written properly, my bad

Answer 8

because work is a scalar quantity measured in joules (energy)
also, work is maximized when the force acts in the same direction as the object moves, so that implies dot product
cross product is maximized when the two are perpendicular, and gives a vector result

Answer 9

the dot product results in a scalar...

Answer 10

yeah, So it depends upon what we have to find

Answer 11

so , here work is scalar , so scalar-product, i see

Answer 12

yep :)

Answer 13

Just a little extra, it seems to me that this is one case where the distinction between newton*meters is really useful to be called Joules instead since there is a slight ambiguity between work and torque as they are both dimensionally Nm.

However the difference between work and torque is the difference between pushing on the door hand normally (torque) and pushing something straight forward where there is no rotation angle.

Answer 14

i see