# An elevator with a wieght of 27.8 kN is given an upward acceleration of 1.22 m/s^2 by a cable. a) what is the tension in the cable. b) what is the tension when the elevator is declerating at the rate of 1.22m/s^2 but is still moving upwards?

what exactly is a kN? to find the tension of part a what equation would I use? for b) I need to make a=-1.22m/s^2 but I am not sure what the equation I would use be.I should be getting 31.3 kN for a) and 24.3kN for part b but I can't figure out my problem.

Tension= mg + ma when going up.

Tension = mg - ma when going down. Think that out.

kN is kiloNewtons

## 27.8*9.81+27.8*1.22=306.634

## To find the tension in the cable, you can use Newton's second law of motion, which states that the net force acting on an object is equal to the mass of the object multiplied by its acceleration.

a) When the elevator is moving upward with an acceleration of 1.22 m/s^2, the equation to find the tension in the cable can be written as:

Tension = mass * (acceleration due to gravity + upward acceleration)

Given that the weight of the elevator is 27.8 kN, you need to convert it to mass by dividing it by the acceleration due to gravity (approximately 9.8 m/s^2):

Weight of the elevator = mass * acceleration due to gravity

27.8 kN = mass * 9.8 m/s^2

Solving for mass:

mass = 27.8 kN / 9.8 m/s^2

Now, substitute the values in the tension equation:

Tension = mass * (acceleration due to gravity + upward acceleration)

Tension = (27.8 kN / 9.8 m/s^2) * (9.8 m/s^2 + 1.22 m/s^2)

Tension ≈ 31.3 kN

So, the tension in the cable when the elevator is accelerating upward is approximately 31.3 kN.

b) When the elevator is decelerating upward at the same rate of 1.22 m/s^2, the equation to find the tension in the cable is:

Tension = mass * (acceleration due to gravity - upward deceleration)

Using the same mass value obtained earlier, substitute the values in the tension equation:

Tension = (27.8 kN / 9.8 m/s^2) * (9.8 m/s^2 - 1.22 m/s^2)

Tension ≈ 24.3 kN

Thus, the tension in the cable when the elevator is decelerating upward is approximately 24.3 kN.

If your calculated values are different, please double-check your calculations or provide the specific steps you are taking so that we can assist you more effectively.