Whats the pareto principle of mechanical engineering?

Assuming weightless pulleys and 100% efficiency, what is the minimum input force required to lift a 120 n weight using a single fixed pulley?

=force × distance a. work b. velocity c. pressure d. momentum

Identify the correct relation showing that the radius r of the orbit of a moon of a given planet can be determined from the radius r of the planet, the acceleration of gravity at the surface of the planet, and the time τ required by the moon to complete one full revolution about the planet. determine the acceleration of gravity at the surface of the planet jupiter knowing that r = 71 492 km and that t= 3.551 days and r= 670.9 × 10^3 km for its moon europa.