Answer:
Potential energy is 
Explanation:
The potential energy depends on the mass, the acceleration of gravity g and the height at which the object or person is.
Potential energy 
In this case we would need to know the exact mass of the hiker in order to calculate the potential energy.
But we know the values of g and h


So, the potential energy

m is the mass of the hiker, wich is not in the description of the problem.
Answer:
it is the judicious use of energy to prevent wastage
Answer:
Part a)
acceleration = -0.042 m/s/s
Part b)
initial speed = 14.17 m/s
final speed = 5.77 m/s
Explanation:
Part a)
Let the initial velocity of the motorcycle is

now at the end of 80 s let the speed is

after another 120 s let the speed will be

now we know that



also we know that

also we have


now we can say

also we know



Part b)
now we have



so the starting velocity of the trip is

now speed after t = 200 s is given as


