Calculating Work Done by Force: Vectors & Joules

[Jbreezy]

The work done (in Joules) by a force in moving a body is calculated by the dot product of the free vector representing the force (in Newtons) by the free vector representing the displacement of the object (in metres).
a. If the magnitude of the force is 4i + 2j -3k Newtons and the displacement vector is <.25,.5,1> metres what is the total work done by the force?

Homework Statement

Solution

I just dotted them.

<4,2,-3> dot <.<.25,.5,1> = 1+ 1 - 3 = -1
Is this correct? The work is - 1?

If this is not correct do not tell me why it isn't rather propose a thought. I don't want the answer given to me. Thanks very much :)

 

[voko]

This is correct. It is really just a dot product.

 

[tiny-tim]

Hi Jbreezy!

Is this correct? The work is - 1?

Yes, that's correct, and perfectly normal …

for example, work done by friction is always negative. ​

 

[Jbreezy]

Thanks very much. People:)