A535 kg roller coaster car began at rest at the top of a 93.0 m hill. now it is at the top of the first loop- de - loop. this roller coasters track is nearly frictionless so, resistances can be ignored. using g= 9.81 m/s^2

The roller coasters, at that point in the first loop-de-loop, it has potential and kinetic energy according to the conservation of energy theorem, because is moving and it's at certain height still.

Remember that conservation of energy theorem states that the total energy of an object is constantly exchanging between potential and kinetic energy, and the total amount of energy is always constant, the variation is between these two energy, but the total amount is always the same.

So, when the roller coaster is at the initial point, it only has potential energy, it's total energy is potential only, because it's not moving. Then, when starts to move, the total energy is distributed into potential + kinetic energy.

this is an example of "committed" time.

committed time, as contracted time, takes need over essential and available time since it is seen as profitable work. it alludes to the time allotted to keep up a home and family. at the point when a man is commuting using committed time this individual may feel that the drive is an obligation to family, for example, strolling youngsters to class or driving a mate to work. contracted and committed time clients may feel that their commute could really compare to the commute of important or leisure time clients on the grounds that their commute is profitable work. in this manner, they might be more disposed to pick a mechanized method of movement.  

conservation of mass

mass before something happens = mass afterwards