Vector Notation for Work: An Exploration of Force and Displacement

[warnexus]

Homework Statement

Homework Equations

Work = F* delta x

The Attempt at a Solution

My thought process since the force is given in vector notations multiply the pair of i components together same applies with j and k components. However this process actually strangely does not work. And I am baffled by why a k component missing for the initial displacement.

 

[Doc Al]

The k component happens to equal 0 at the initial position. So what?

Figure out the displacement: r₂-r₁

 

[warnexus]

after substraction I get 5 i - 21 j + 14k.

5i(67i) + 23j(-21j) + 55k(14k) = 335 - 483 + 770 = 622 J <- correct! =]

thanks for the guidance, Doc Al.