# simple clarification

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• Jan 24th 2010, 10:58 PM
furor celtica
simple clarification
ok this is a kinematics thing.
s(displacement)=93, v(end velocity)=42, t(time)=3/2, find a (acceleration)
so i used s= vt -0.5at^2 and got a= -80/3
however the answer is (+ or -) 80/3, and i dont know why. can someone clarify?
• Jan 25th 2010, 04:30 AM
CaptainBlack
Quote:

Originally Posted by furor celtica
ok this is a kinematics thing.
s(displacement)=93, v(end velocity)=42, t(time)=3/2, find a (acceleration)
so i used s= vt -0.5at^2 and got a= -80/3
however the answer is (+ or -) 80/3, and i dont know why. can someone clarify?

Post the entire question with the original wording (if it was in English).

It is possible that there is a type in the answers.

CB
• Jan 25th 2010, 08:12 AM
avengerevenge
Quote:

Originally Posted by furor celtica
ok this is a kinematics thing.
s(displacement)=93, v(end velocity)=42, t(time)=3/2, find a (acceleration)
so i used s= vt -0.5at^2 and got a= -80/3
however the answer is (+ or -) 80/3, and i dont know why. can someone clarify?

Actually when u get a negetive value like u got here a= -80/3, you keep modulus to the
number or expression like this"|-80/3|",( the two dashes which are called as modulus) the function of modulus is to neglect any negetive values so that we can write in positve value,

example:- a = -80/3 when moudulus is placed |a|=|-80/3| which becomes a=80/3,

so my point is that when modulus is present from starting point of the question, if we remove the modulus from there(question) then the question becomes (+ or -) from there it self,

watch your question again if there is modulus present in it.
• Jan 26th 2010, 09:28 PM
furor celtica
captain black there was no text to accompany this exercise, it was a part of a long list of similar mechanics problems
what do you mean by "It is possible that there is a type in the answers"