Correct answer only !

as a roller coaster goes downhill

a) kinetic energy is converted into potential energy.

b) potential energy is converted into kinetic energy.

c) electrical energy is converted into potential energy.

d) potential energy is converted into electrical energy.

Inelastic is the answer your looking for.

I'm pretty sure the answer is c 

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.