Answer:
when a force is applied by one object to a second object, an equal and opposite force is applied back on the first object
Explanation:
The correct answer is:
Work is negative, the environment did work on the object, and the energy of the system decreases.
In fact, the work-energy theorem states that the work done by the system is equal to its variation of kinetic energy:

In this problem, the variation of kinetic energy
is negative (because the final velocity is less than the initial velocity), so the work is negative, and this means that the environment did work on the object, and its energy decreased.
Answer:
So coefficient of kinetic friction will be equal to 0.4081
Explanation:
We have given mass of the block m = 0.5 kg
The spring is compressed by length x = 0.2 m
Spring constant of the sprig k = 100 N/m
Blocks moves a horizontal distance of s = 1 m
Work done in stretching the spring is equal to 
This energy will be equal to kinetic energy of the block
And this kinetic energy must be equal to work done by the frictional force
So 


So coefficient of kinetic friction will be equal to 0.4081
Given :
Number of operations move through a pocket calculator during a full day's operation ,
.
To Find :
How many coulombs of charge moved through it .
Solution :
We know , charge in one electron is :

So , charge on n electron is :

Therefore , -21.44 coulombs of charge is moved through it .
Hence , this is the required solution .