A person who has a mass of 55 kg is standing in an elevator which is accelerating downward. Acceleration due to gravity is 10 m/s2. a) At what rate (in m/s2) must the elevator accelerate for the person to feel weightless

10 m/s²

Explanation:

The reaction on a person in an elevator that is descending  is given as

R = m(g-a) Equation 1

Where R = apparent weight of the person inside the elevator, g = acceleration due to gravity, m = mass of the person, a = acceleration of the elevator.

make a the subject of the equation

a = g-(R/m) Equation 2

Note: For weightlessness, R = 0 N.

Given: g = 10 m/s², R = 0 N (weightlessness). m = 55 kg

Substitute into equation 2

a = 10-(0/55)

a = 10-0

a = 10 m/s²

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.

it would be kevlar ^^