The atmospheric pressure at sea level is 1.01x10° Pa. The mass of air column per 10 cm? at sea is (take g=9.8 m/s)

The boat's velocity relative to the riverbank can be resolved into two components. the component going north is 2.7 m/s and the component going west is 1.2 m/s.we add these two vectors and then find the magnitude of the resultant to get the speed.the magnitude of the resultant vector from adding can be obtained by the pythagorean theorem.    to two significant figures, the boat's speed relative to the riverbank is 3.0 m/s.

Iwould say earthquakes.

Decrease the surface area of the object and also decrease the concentration which will allow the particles to collide faster