Question

Determine the force in member ab, and state if the member is in tension or compression.

Answer 1

for this problem the following concepts need to be clear.  

1) The tension: it is when the forces go outwards, for example the cable of a lamp that hangs, one force is the ceiling and the other, the weight of the lamp.

2) Compression: it is when external forces are made from the outside towards the center.