The device is used for surgical replacement of the knee joint. If the force acting along the leg is 360 N, determine its components along the x and y’ axes.

#### Solution:

### Let us first draw the vector components as follows:

### As stated in the question, the force components are directed along the x-axis and the y’-axis.

### Now, we will draw the vectors tail to tail as follows:

### Now we will use sine law to figure out F_x and F_{y'}

### \frac{-F_x}{\sin20^0}=\frac{360}{\sin100^0}

### F_x=-125N (negative because the force is directed along the negative x-axis)

### \frac{F_{y'}}{\sin60^0}=\frac{360}{\sin100^0}

### F_{y'}=317N

###### This question can be found in Engineering Mechanics: Statics (SI edition), 13th edition, chapter 2, question 2-13.

Why can’t I just use cosine 60 to find the component of x? Is it because when the arrows are drawn head to tail the triangle formed is not a right angle triangle?

That is correct. 🙂

Please how did we get that 60degrees on the negative x axis??

Use the parallel angle laws to get them.

why this calculation is important for the intended

application.

It could be to figure out limitations so we can create something that’s suitable and able to take the forces that’s put on it.

Thankyou so much♥️

You’re very welcome!