A roller coaster with a potential energy of 235,200 J sits at the top of a 30 m high hill. What is the mass of the roller coaster? (Formula: PE = mgh)

How did the construction of the erie canal improve transportation in the united states in the 1820s? a. the canal connected the great lakes to the mississippi river. b. the canal connected the great lakes to the ohio river. c. the canal connected the atlantic and pacific oceans. d. the canal connected the great lakes to the atlantic ocean.