Question
- Find the function
f
such thatf'' = -f
- Show that the function can be written in format
f = A sin(x + B)
Extension
Find a function g
such that g'' = C * -g
and
g(0) = D
g'(0) = 0
whereC
andD
are arbitrary constants.
For those who have finished the extension
Congratulations, you have just derived the formula for objects in simple harmonic motions (physics).
That’s why one usually searches for non trivial solution of differential equations. The trivial solution f(x)=0, in physics: “nothing happens”, is usually not of interest, as we know by experience that something must happen to a system when some initial action is performed, yet mathematically it is always there.