1. Dec 11, 2016

### williamwong0402

• Member warned that an effort must be shown, and the homework template is required
Hi everyone

how can i find the force in Q(a)(ii)?

2. Dec 11, 2016

### Andrew Mason

Welcome to PF William!

A unit vector is just the vector ie. (x, y z) divided by its length. What is the length of this vector (1,1,1)?

You must then express the force as a vector by multiplying the magnitude of tbe force (14 N) by the unjt vector in the direction of that force.

Can you provide us with the expression for Work in terms of the information provided?

AM

3. Dec 11, 2016

### williamwong0402

like this?
but how can get force of vector by multiplying

4. Dec 11, 2016

### Buffu

I did not get it. Can you please state it clearly.
But I guess you mean how to express Force in vector form. That is simply ${14\over\sqrt{3}}\hat{i} + {14\over\sqrt{3}}\hat{j} +{14\over\sqrt{3}}\hat{k}$.

For (iv) you need to take dot product of (ii) and (iii). $(\vec{A}\cdot\vec{B} = A_xB_x + A_yB_y + A_zB_z)$

5. Dec 11, 2016

### williamwong0402

Thank you ~i got it
i just thought the other way more complex