You set up a pulley to you lift something. you anchor the rope at one end and arrange a moveable pully to achieve a mechanical advantage of 2. by the time you have lifted the object 5m off the ground, how much rope have you pulled through the pulley?

Automobile fuel efficiency is often measured in miles that the car can be driven per gallon of fuel (mpg). heavier cars tend to have lower fuel efficiencies (lower mpg ratings). which variable (weight or fuel efficiency) is most naturally considered the explanatory (predictor) variable in this context?