An ergonomically designed key for a computer keyboard has an approximately flat surface define by points A, B, and C and is subjected to a 1 N force in the direction normal to the key’s surface.  

(a) In Fig. P2.157(a), motion of the key is in the z direction. Determine the components of the force in directions normal and tangent to the key’s motion. Comment on why it might be important to know these components.

  

(b) In Fig. P2.157(b), the switch mechanism is repositioned so that the motion of the key is in the direction of the line connecting points D and E, where this line has x, y, and z direction cosines of 0.123, 0.123, and 0.985, respectively. Determine the components of the force in directions normal and tangent to the key’s motion. Comment on why this design might be more effective than that in Part (a).

     

      

(15,0, 10) mm 2 (0, 0, 15) mm (), 15, 12) mm Z. E 1N 1N C A A, y D () (b) Figure P2.157