Magnetic fields can go through some materials (like cardboard). Electric fields can also do that. Electromagnetic waves can do that. It’s not at all unusual because magnetic fields are not made up of particles so they can go through materials.
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Answer:
N = 648.55[N]
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.

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]](https://tex.z-dn.net/?f=-%2873.2%2A9.81%29%2BN%3D-73.2%2A0.950%5C%5C-718.092%2BN%3D-69.54%5C%5CN%20%3D%20-69.54%2B718.092%5C%5CN%20%3D%20648.55%5BN%5D)
The acceleration has a negative sign, this means that the elevator is descending at that very moment.
Explanation:
a. Mechanical advantage = force out / force in
MA = 830 / 100
MA = 8.3
b. Efficiency = work out / work in
0.80 = W / 600 J
W = 480 J