Bohr's model of the atom included a positively charged orbited by negatively charged nucleus, protons nucleus, electrons neutrons, electrons protons, electrons

May someone explain how to do this question?

The friction of the water on a boat produces an acceleration of -10. m/s2. if the boat is traveling at 30. m/s and the motor is shut off, how long it take the boat to slow down to 5.0 m/s?

What energy transformations occur each time the skateboarder rolls up the ramp?