When rolling downhill, a roller coaster's gravitational potential energy changes its form many times. Identify the form(s) of energy that it will become throughout the ride. a

kinetic (motion) energy.

b

thermal energy.

c

sound energy.

d

All of the above

The particle p starts from rest at point a at time t = 0 and changes its speed thereafter at a constant rate of 2.8g as it follows the horizontal path shown. determine the magnitude and direction of its total acceleration (a) just before point b, (b) just after point b, and (c) as it passes point c. state your directions relative to the x-axis shown (ccw positive) and choose the angle with the smallest magnitude.