Defining a Step Function: Checking for Accuracy

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The discussion focuses on defining a step function using the Heaviside unit step function, u(t). The initial definition presented is C[-u(t) + u(-t)], but concerns are raised about its accuracy, particularly regarding the behavior at t = 0. It is noted that the function should be expressed in terms of u(t) for engineering purposes, and the proposed definition may not hold for all values of t. An alternative definition, C[1-2u_c(t)], is suggested as it appears to work for all real numbers. The conversation emphasizes the need for clarity in defining step functions in engineering contexts.
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I just want to check if I got this right.
Given this graph, I need to define a step function:
Code:
         |
---------| C
         |
_________|_______________
         |
      -C |_________
         |

So, my definition is: C[-u(t) + u(-t)].
Thanks for checking this.
 
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f(x) = {c, x < 0}{-c, x > 0}, f(x) is undef at x = 0, though, |f(0)| = c
 
Thanks for reply.

I understand the form of the function, but this is for an engineering class, so we have to express everything in terms of u(t), etc. So, this is what I need for some-one to double check.
And they actually never say that there is a discontinuity at 0, because we have to find values for t >=0 and so on.
 
I don't think your definition will work so well. Let's say 0<c, and 0<t<c. What is the value of your function? well u_c(t)=0 \mbox{ for } t&lt;c \mbox{ and } u_c(-t)=0 \mbox{ for } t&lt;c since t will just be negative it will still be less than c. So your function will not work in that case. I just worked from left to right to construct the definiton and came up with
C[1-2u_c(t)]

Which seems to work for all t in R.

Regards
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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