Answer:
The gravitational force on the elevator = 4500N
Explanation:
The given parameters are;
The force applied by the elevator, F = 4500 N
The acceleration of the elevator = Not accelerating
From Newton's third law of motion, the action of the cable force is equal to the reaction of the gravitational force on the elevator which is the weight, W and motion of the elevator as follows;
F = W + Mass of elevator × Acceleration of elevator
∴ F = W + Mass of elevator × 0 = W
F = 4500 N = W
The net force on the elevator is F - W = 0
The gravitational force on the elevator = W = 4500N.
A mixed cost contains a variable element and a fixed element.
Option a
<u>Explanation:</u>
Mixed costs are those costs that has both variable and fixed component. Example: operating cost of a machinery includes fixed costs that cannot be changed with other variable costs like fuel, insurance, depreciation, etc.
It is also named as semi-variable costs. And the formula to calculate mixed cost is as follows,

where,
- y is the "total cost
"
- a is the "fixed cost per period"
- b is the "variable rate per unit of activity"
- x is the "number of units of activity"
The first ariplanr was made December 17, 1903
Passengers in an aircraft are subject to the Normal and Gravity Force acting on them at a low 'orbit', so tiny that it can be many times compared to the same surface of the earth when speaking in general terms.
In a high orbit space vehicle or in the same space, said force decreases considerably or simply disappears, generating the sensation of weightlessness.
Remember that the Force of Gravity is given under the principle

Where,
G = Gravitational Universal constant
M = Mass of the planet
m = mass of the object
r = Distance from center of the planet
When the radius grows considerably the gravitational force begins to decrease.