A lever and fulcrum are used to raise a heavy rock, which has a weight of 356.7 N. If the lever has a mechanical advantage of 8.7, what must the input force on the lever be in order to just begin lifting the rock?

Thermal stresses are developed in a metal when its a) initial temperature is changed b) final temperature is changed c) density is changed d) thermal deformation is prevented e) expansion is prevented f) contraction is prevented

In general, how do thermosetting plastics compare to thermoplastics in mechanical and physical properties?

A)-in the process of engineering design, explain the contribution of material selection. b)- explain the procedure of synthesis as is employed in engineering design. c)- is there any relationship between ergonomics and engineering design? explain. d)- safety consideration in engineering design includes human, product and the enviroment . explain how safety will be incorporated into the design?