Question

Shelley is in an elevator that is traveling downward and slowing down at a rate of

0.950 m/s2. If Shelley has a mass of 73.2 kg, what is her apparent weight during this
period?

Answer 1

N = 648.55[N]

Step-by-step explanation:

To solve this problem we must use Newton's second law which tells us that the sum of forces on a body is equal to the product of mass by acceleration.

∑F = m*a

where:

∑F = Forces applied [N]

m = mass = 73.2 [kg]

a = acceleration = 0.950 [m/s²]

Let's assume the direction of the upward forces as positive, just as if the movement of the box is upward the acceleration will be positive.

By performing a summation of forces on the vertical axis we obtain all the required forces and other magnitudes to be determined.

`-m*g + N = -m*a\\`

where:

g = gravity acceleration = 9.81 [m/s²]

N = normal force (or weight) measured by the scale = 83.4 [N]

Now replacing:

`-(73.2*9.81)+N=-73.2*0.950\\-718.092+N=-69.54\\N = -69.54+718.092\\N = 648.55[N]`

The acceleration has a negative sign, this means that the elevator is descending at that very moment.