Answer:
D
friction acts in the opposite direction of motion but does not affect the motion of the object
Answer: Electromagnetic radiation
Explanation:
Electromagnetic radiation is a combination of oscillating electric and magnetic fields, which propagate through space carrying energy from one place to another.
To understand it better:
This radiation is spread thanks to the electromagnetic fields produced by moving electric charges and their sources can be natural or man-made.
It should be noted that the energy of electromagnetic radiation can vary and depending on its frequency it can be useful for various situations.
The question doesn't describe any experiment. If the same experiment is repeated, no matter how many times, the acceleration due to gravity will remain the same as it was during the non-existent original experiment, and will have no effect on anything.
By the work energy theorem, the total work done on the stone is given by its change in kinetic energy,
![W = \Delta K = \dfrac m2 ({v_2}^2 - {v_1}^2)](https://tex.z-dn.net/?f=W%20%3D%20%5CDelta%20K%20%3D%20%5Cdfrac%20m2%20%28%7Bv_2%7D%5E2%20-%20%7Bv_1%7D%5E2%29)
We have
![\vec v_1 = (6.60\,\vec\imath - 2.40\,\vec\jmath)\dfrac{\rm m}{\rm s} \implies {v_1}^2 = \|\vec v_1\|^2 = 49.32 \dfrac{\rm m^2}{\rm s^2}](https://tex.z-dn.net/?f=%5Cvec%20v_1%20%3D%20%286.60%5C%2C%5Cvec%5Cimath%20-%202.40%5C%2C%5Cvec%5Cjmath%29%5Cdfrac%7B%5Crm%20m%7D%7B%5Crm%20s%7D%20%5Cimplies%20%7Bv_1%7D%5E2%20%3D%20%5C%7C%5Cvec%20v_1%5C%7C%5E2%20%3D%2049.32%20%5Cdfrac%7B%5Crm%20m%5E2%7D%7B%5Crm%20s%5E2%7D)
![\vec v_2 = (8.00\,\vec\imath + 4.00\,\vec\jmath) \dfrac{\rm m}{\rm s} \implies {v_2}^2 = \|\vec v_2\|^2 = 80.0\dfrac{\mathrm m^2}{\mathrm s^2}](https://tex.z-dn.net/?f=%5Cvec%20v_2%20%3D%20%288.00%5C%2C%5Cvec%5Cimath%20%2B%204.00%5C%2C%5Cvec%5Cjmath%29%20%5Cdfrac%7B%5Crm%20m%7D%7B%5Crm%20s%7D%20%5Cimplies%20%7Bv_2%7D%5E2%20%3D%20%5C%7C%5Cvec%20v_2%5C%7C%5E2%20%3D%2080.0%5Cdfrac%7B%5Cmathrm%20m%5E2%7D%7B%5Cmathrm%20s%5E2%7D)
Then the total work is
![W = \dfrac{2.40\,\rm kg}2 \left(80.0\dfrac{\rm m^2}{\rm s^2} - 49.32\dfrac{\rm m^2}{\rm s^2}\right) \approx \boxed{36.8\,\rm J}](https://tex.z-dn.net/?f=W%20%3D%20%5Cdfrac%7B2.40%5C%2C%5Crm%20kg%7D2%20%5Cleft%2880.0%5Cdfrac%7B%5Crm%20m%5E2%7D%7B%5Crm%20s%5E2%7D%20-%2049.32%5Cdfrac%7B%5Crm%20m%5E2%7D%7B%5Crm%20s%5E2%7D%5Cright%29%20%20%5Capprox%20%5Cboxed%7B36.8%5C%2C%5Crm%20J%7D)