Final answer:
Lifting a 70-kilogram barbell 2.0 meters above the floor increases its potential energy by approximately 1372 joules.
Step-by-step explanation:
The potential energy of an object can be calculated using the formula PE = mgh, where PE is the potential energy, m is the mass of the object, g is the acceleration due to gravity, and h is the height above the reference point. In this case, the mass of the barbell is 70 kilograms, and the height it is lifted is 2.0 meters. Substituting these values into the formula, we get:
PE = (70 kg) * (9.8 m/s^2) * (2.0 m) = 1372 J
Therefore, lifting the 70-kilogram barbell 2.0 meters above the floor increases its potential energy by approximately 1372 joules, which is closest to option D, 1,400 joules.