The position function of an object moving horizontally along a straight line as a function of time is s(t) = t^2 -3t +2, t≥0, in metres, at time t, in seconds.

a) Determine the speed of the object when the position is 0.
answer: 1 m/s

Isn't the answer 1 m/s AND -1m/s? That's what I get when I plug in t=2 and t=1 in the function

b) When does the object move to the left?
answer: between 0s and 1.5s

Does between mean that it includes the value? since the question states that t≥0, shouldn't the answer be 0≤t

Question

The position function of an object moving horizontally along a straight line as a function of time is s(t) = t^2 -3t +2, t≥0, in metres, at time t, in seconds.

a) Determine the speed of the object when the position is 0.
answer: 1 m/s

Isn't the answer 1 m/s AND -1m/s? That's what I get when I plug in t=2 and t=1 in the function

b) When does the object move to the left? 
answer: between 0s and 1.5s

Does between mean that it includes the value? since the question states that t≥0, shouldn't the answer be 0≤t<(3/2)?

anonymous · Answer

I can see your point of view for both of these questions.
For the first one the reason why they may be saying that only 1 m/s is the answer is because speed is the absolute value of velocity (which is what you get when you say 1 m/s and -1m/s). So the absolute value of 1 is 1 and the absolute value of -1 is 1 as well.
Or at least that is the only reasoning I can come up with.

anonymous · Answer

As for your second question, I believe you are correct in saying that it is inclusion so $$0\le t \le 3/2$$ 
Since technically on the graph of the position it is decresing from 0 to 1.5 and increasing from 1.5 to infinity.

anonymous · Answer

Does that help?

he66666 · Answer

Thanks so much! I understand it now :)

anonymous · Answer

Glad that I could clarify.