5. A 1500 kg roller coaster car starts from rest at a point 45 m above the bottom of a dip. It then goes down to the bottom and climbs another hill with a height of 30 m. 45m 30m :1. What is the potential energy at the top of the 45 m hill? b. What is the velocity of the roller coaster at the bottom of the dip? c. What is the velocity of the roller coaster at the top of the 30 m hill