How much work is done by the force lifting a
0.1-kilogram hamburger vertically upward at
constant velocity 0.3 meter from a table?
(1) 0.03 j (3) 0.3 j
(2) 0.1 j (4) 0.4 j

The work done in lifting the hamburger is equal to the increase in gravitational potential energy of the hamburger, given by

where

m=0.1 kg is the mass of the hamburger

is the gravitational acceleration

is the increase in height of the hamburger

Substituting numbers into the equation, we find

So, the correct answer is

(3) 0.3 J

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it