The answer is D using the work formula
W= F•d but if it was against gravity, it would be 0 if gravity is exerting the same amount, I would pick D using the formula, but I'm not so sure sorry
Explanation:
When you observe the night sky you will notice that the stars are moving. They rise from eastern horizon and set in the western horizon. It happens due to rotation of Earth. When observed closely you will notice that the all the stars seem to go around the pole star. Out of all the stars there are some stars which neither set not rise, such stars are called as Circumpolar stars. This means that they are always above the horizon. If we trace the path of such stars they will appear to make complete circle around the pole star.
Also, you will notice that the altitude of pole star (separation of pole star from the horizon in degrees) will depend on the location of observe on the Earth. This happens due to Earth being spherical. So if you are on equator the pole star will be on the horizon i.e. 0° altitude. If you are at Poles, altitude of the pole star will be 90°. Technically the altitude of pole star at any place on Earth is equal to the latitude of the place.
If the altitude of pole star varies and increases as you move towards higher latitude on Earth, the distance between horizon and pole star will also increase. This will result in more stars being circumpolar.
If you are at Poles, all the stars will be circumpolar and if you are at equator no star will be circumpolar.
Enclosed is some guidance algebra.I find this q a little confusing. It quotes "RC" which usually makes me think of electrical circuits and time constants based on converting calculating RC value and equating that to t for one time constant then 2RC for two time constants etc. The theory being that after 5 time constants - 5RC - a circuit is stable. BUT, this q then goes on to mention HALF LIFE. The curves for both half life and time constant are both exponential, as in the number e to the power of something, but the algebra is slightly different. I hope my algebra is ok.
The vector, the x-component and the y-component form a rectangle triangle where the vector is the hypothenuse and the x and y components are the two sides.
Calling
![\alpha](https://tex.z-dn.net/?f=%5Calpha%20)
the angle between the vector and the horizontal direction (x), the two sides are related to
![\alpha](https://tex.z-dn.net/?f=%5Calpha%20)
by
![\tan \alpha = \frac{v_y}{v_x}](https://tex.z-dn.net/?f=%5Ctan%20%5Calpha%20%20%3D%20%20%5Cfrac%7Bv_y%7D%7Bv_x%7D%20)
where vy and vx are the two components on the y- and x-axis. Using vx=10 and vy=3 we find
![\tan \alpha = \frac{3}{10} =0.3](https://tex.z-dn.net/?f=%5Ctan%20%5Calpha%20%20%3D%20%20%5Cfrac%7B3%7D%7B10%7D%20%3D0.3)
And so the angle is