<span>Fasteners are double or triple threaded with the idea of durability. People look for durability in a fastener and if they receive one with triple threaded or double threaded they will feel more safe and at ease knowing it has extra strength added.</span>
C) total linear momentum of the ball and cannon is conserved.
Basically it happens that in the beginning before there is a momentum acting on the two bodies, these are a unique system. Here the total momentum of the System is 0. However, when the positive momentum of the cannonball is added, the system will be immediately affected by a negative momentum which will pull back the cannon. Could this be extrapolated as a condition of Newton's third law.
A bowling ball because it is heavier and it has more air force going against it<span />