It would need to be over 20 because if the load of the Pulley E is 20 and the effort is 20, then they will be equal and the Pulley would not move, so your answer is at least 20
The answer is B. I hope this helps! :)
If stars never changed, then constellations wouldn't change. But the stars, including the Sun, travel in their own separate orbits through the Milky Way galaxy. The stars move along with fantastic speeds, but they are so far away that it takes a long time for their motion to be visible to us.
When temperature increases a solid can melt to a liquid and a liquid can turn to gas.