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(a) A particle has ~r(0) = (4 m)j and ~v(0) =

(2 m/s)i.

If its acceleration is constant and given by

~a = −(2 m/s2) (i+j), at what time t does the

particle first cross the x axis?

Answer in units of s.

(b) At what time t is the particle moving parallel to the y axis; that is, in the j direction

Answer in units of s

2.Some equation with a constant acceleration... not sure which one

3. I tired to draw it out but I don't know how... I don't understand how to start the problem

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# Homework Help: What time t does the particle first cross the x axis?

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