The force required to lift the load is its weight.
Weight = (mass) x (gravity)
so Work = (mass) x (gravity) x (distance)
Now Power = (work) / (time)
so Power = (mass) x (gravity) x (distance) / (time)
= (700kg) x (9.8 m/s²) x (2 m) / (0.4 sec)
= ( 700 x 9.8 x 2) / (0.4) (kg-m²/sec²) / (sec)
= ( 34,300 ) (joule) / (sec)
= 34,300 watts .
This is one of those exercises where the math and the physics are air-tight and bullet-proof but the answer is absurd.
34,300 watts is about 46 horsepower. I don't care how many Wheaties Power Lifter Paul had for breakfast today, he is NOT snatching a barbell that weighs 1,543 pounds (0.77 ton !) to the height of the top of his head in less than 1/2 second !
(D) The gravitational force between the astronaut and the asteroid.
Reason:
All the other forces given in the options, except (D), doesn't account for the motion of the astronaut. They are the forces that act between nucleons or atoms and neither of them accounts for an objects motion.
