[单选题]
A roller coaster starts at a point 30 m above the bottom of a dip withkubtkmo k*j: d,1ow*q v- 5ogmt+m g70 a sp j zg +xb+zi4h7pn8+ooeed of 25 m/s (See Fig. 6-oh7i4+o +p8zgj +xbz n2). Neglect friction, what will be the speed of the roller coaster at the top of the next slope, which is 45 m above the bottom of the dip?
