# "nonlinear mechanical effect" on a pendulum

Discussion in 'MCAT Study Question Q&A' started by sc4s2cg, 06.14.12.

1. ### sc4s2cg

Joined:
05.24.10
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Medical Student

What does that mean?

PBRI 5.1, #6:

What is an example of a nonlinear mechanical effect?

a) Air resistance caused by localized eddies in the evacuated jar
b) Thermal expansion of the fulcrum due to friction
c) Induced electrical current in the moving bob
d) Deformation of the cable caused by centripetal acceleration

Answer is D, but I am unfamiliar with the terms "nonlinear mechanical effect" and "eddies".
2. ### RocketSurgeon

Joined:
12.25.10
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Status:
Pre-Medical
Linear implies in 2-D an equation the form y = mx + b. If you plot x and y you get a straight line in 3-D you get a plane z = ax + by + c. Google this "plot 3x+4y+4"

Non-Linear equations have a higher order polynomial term or non linear terms in the equations for example. max operator max(a,b) or y = (x^2).

Deformation of a cable is non linear because if force x increases by one unit the length y does not increase in the form y = mx + b but in some non linear way for example y = log(x).

A visual way to think of this is

Increase -->
Force : |_|_|_|_|_|_|_|_|_|
Length : |_|__|___|____|_____|

Hope this helps