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

the second one and the forth one are in the purple because they are opinions and the rest are in the yellow

explanation:

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards