Because some of the energy is wasted and the amount of energy wasted is based on the efficiency of the machine
Answer:
Work done in both the cases will be same
Explanation:
As we know that the work done against gravity is given as

here we know that gravitational force is a conservative force and the work done against gravitational force is independent of the path
So here the work done by person to move the object between two different heights will be independent of the path they choose
So for the first person and second person will be same in both the cases because the height through which the boxes are transferred will be same in both the cases
Answer:
B
Explanation:
kinetic energy (KE) is the energy possessed by moving bodies. It can be expressed as:
KE =
m
Where: m is the mass of the object, and v its speed.
For example, a stone of mass 2kg was thrown and moves with a speed of 3 m/s. Determine the kinetic energy of the stone.
Thus,
KE =
x 2 x 
= 9
KE = 9.0 Joules
Assume that the speed of the stone was 4 m/s, then its KE would be:
KE =
x 2 x 
= 16
KE = 16.0 Joules
Therefore, it can be observed that as speed increases, the kinetic energy increases. Thus option B is appropriate.