The forces are gravity (weighing down) and internal gas pressure (pushing away from the surface).
Work done = Force x Distance
Force = 10 lb = 44.5 N
Work Done = 44.5 N x 15 m
= 667.5 N-m
Answer: Physiologic response to fear is very similar to that of PTSD and stress. Fear is accompanied by increased heart rate due to the release of adrenaline, sympathetic nervous system is aroused. The release of adrenaline also causes increased sweating, pulse and blood pressure. In line with this, the parasympathetic nervous system experiences reduced activity such as decrease in digestion.
add the river's velocity to the boat's velocity
5+ 5 = 10 km/h
Hope this helps!