I'm afraid I'm not seeing how proportionality comes into play here...?
You're given the position function (the distance from point O) as a function of time, and are asked for the acceleration function. So differentiate twice.
Geez i dunno if this is even direct or inverse proportionality, or if this threads even in the right section :S sorry, first time here!
But anyway, to the question..
"A particle moves along a line.
For 't' bigger than or equal to 1, the distance of the particle from 'O' at time 't' seconds is 'x' metres, where:
Find an expression for the acceleration of the particle"
Question taken from an IGCSE paper im stuck on.. dont really understand how to solve it at all
Thanks in advance!