1) a 2000 kg car is traveling at 30 m/s on a level road .

a) what is the car's kinetic energy ?
b) what is the car's potential energy ?
c) what is the car's mechanical energy ?

2) mark has a mass of 55 kg and climbs up a short, steep trail of length 300 m to reach the top of a 100 m tall cliff. matthew , his twin brother, walks up a gentle, winding trail of length 500 m to reach the top of the same cliff. what is the potential energy of each boy at the top?

3- death valley, california , has an elevation of 86 meters below sea level. what is the potential energy of a 60 kg teacher in death valley?

The following equations show how kinetic energy (KE), potential energy (PE), and total mechanical energy (ME) are solved. 
                          KE = 0.5mv²
                          PE = mgh
                          ME = PE + KE
where m is mass, v is speed/velocity, g is gravitational constant, and h is height. 
Substituting for number 1,
                          KE = 0.5(2000 kg)(30 m/s)²  900,000 J
                           PE = (2000 kg)(9.8 m/s²)(0 m) = 0
                            ME = 900,000 J

I believe you will be able to answer the rest of the items following the same principles as presented above. 

Amethod of procedure that has characterized natural science since the 17th century, consisting in systematic observation, measurement, and experiment, and the formulation, testing, and modification of hypotheses.

Ireally don’t know