Answer:
C or D i would think would be the answer
The ball is in the air for 27.70m because
9.5+9.7=19.2...
9.7-1.2=8.5...
19.2+8.5=27.70...
Answer:
a = - 1.47 [m/s²], descending or going down
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 = 10 [kg]
a = acceleration [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.

where:
g = gravity acceleration = 9.81 [m/s²]
N = normal force measured by the scale = 83.4 [N]
Now replacing:
![-(10*9.81)+83.4=10*a\\-14.7=10*a\\a=-1.47[m/s^{2} ]](https://tex.z-dn.net/?f=-%2810%2A9.81%29%2B83.4%3D10%2Aa%5C%5C-14.7%3D10%2Aa%5C%5Ca%3D-1.47%5Bm%2Fs%5E%7B2%7D%20%5D)
The acceleration has a negative sign, this means that the elevator is descending at that very moment.
Power
is calculated by dividing the work done with the time interval of the motion.
Work, on the other hand, is force times the distance traveled. Therefore, we
can calculate as follows:<span>
Power=W/t = mgd/t
90 = 60(9.81)d / 40
d = 6.12 m
Number of steps = 20/6.12 = 3.27 or 3 steps</span>
Answer:
Hence, option (A) is correct answer.
Explanation: