3. What is the final speed of the roller coaster shown in the figure if it starts from rest at the top of the 20.0 m hill and work done by frictional forces is negligible? The gravitational acceleration on Earth's surface is 9.8 m s-2. (A)2.4 m/s (B) 4.9 m/s (C) 9.8 m/s (D) 19.8 m/s (E) 29.4 m/s