A spiral staircase in a building is in the shape of a helix of radius 5 meters. Between two oors of the building, the stairs make one full revolution and climb by 4 meters. A person carries a bag of groceries up two oors. The combined mass of the person and the groceries is 70 kg and the gravitational force is 70g downward, where g is the acceleration due to gravity. Use a line integral to calculate the work done by gravity against the person.

2744Nm

Explanation:

The gravitational field is conservative. The gravitational force only acts on a vertical direction. Hence, independently of the form of the trajectory, the work done by the gravity against the person demands the calculation of the integral of the force multiplied by the vertical displacement of the person:

where we have taken that the displacement of the person h=z and df=dz.

hope this helps!!

freezing

deposition

condensation

explanation;

melting also called fusion is the process where solid becomes liquid, sublimation is the process where solid becomes gaseous without first changing to liquid, deposition involves change from gaseous to solid state, freezing involves change from liquid to solid, boiling or evaporation involves change of liquid to gaseous state, while condensation is the change from gaseous state to liquid state.

endothermic reactions involves absorption of heat from the surroundings or the environment while exothermic reactions involves loss of heat energy to the surroundings.

in this case, sublimation, evaporation and melting are endothermic reactions (gain energy from the environment) while, freezing, deposition and condensation are exothermic (loss of energy to the surroundings) reactions.

i think the answer is a, hope this is right, that would be my best guess.