<u>Answer:</u>
148.4 J
<u>Explanation:</u>
We are given that the efficiency of a pulley system is 74.2% and we are to calculate the useful work done if we perform 200 J of work
We know that efficiency is basically the measure of how efficient a process is.
The formula of efficiency is given by:
<em>Efficiency = useful energy output / total energy input</em>
So substituting the given values in the above formula:
0.742 = Useful energy / 200 J
Useful energy = 148.4 J
Answer:
The correct answer is ii) It must revolve around a star
Explanation:
For a celestial body to be called a planet, it must meet at least three characteristics
* rotate around a star
* its mass must be sufficient to maintain hydrostatic equilibrium
* have control over its orbital that is to say to prevent that other body is in its same orbital
if we check the different proportions
i) False. Most of the planets are spheres deformed by their rotation on themselves and around the star
ii) True. It is in accordance with the minimum characteristics of the plants
iii) False .. the orbit of the planet can be elliptical and the speed changes at each point for this at a different distance from the star that is in a focus of the ellipse.
The correct answer is ii) It must revolve around a star
1.) is gonna be one or two 2.) one
Answer:
the moon, earth, and sun all must be in alignment ; not just the moon and earth