)you carry a 7.0 kg bag of groceries 1.2 m above the ground at constant velocity across a 2.7 m room. how much work do you do on the bag in the process

M = 7.0 kg, the mass of the groceries
h = 1.2 m, the elevation of the bag of groceries

The bag of groceries moves a constant velocity over the 2.7-m room.
At constant velocity, there is no applied force, and the kinetic energy remains constant.

At an elevation of 1.2 m, there is an increase in PE (potential energy) given by
V = m*g*h
    = (7.0 kg)*(9.8 m/s²)*(1.2 m)
    = 82.32 J

The change in PE is equal to the work done.

82.3 J

No it doesnt because it can be any number.

The correct answer is  "c".  it is "c" because melting is an endothermic change, and endothermic get's energy from surroundings.