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**A position-time graph for a particle moving along the x-axis is shown below:**

(a) Find the average velocity in the time interval

(b) Determine the instantaneous velocity at

(c) At what value of

(a) Find the average velocity in the time interval

*t*= 1.50 s to*t*= 4.00 s.(b) Determine the instantaneous velocity at

*t*= 2.00 s by measuring the slope of the tangent line shown in the graph.(c) At what value of

*t*is the velocity zero?http://img241.imageshack.us/img241/1514/tangetsb6.jpg [Broken]

I figured that (a) was the easy part as I went ahead to solving that

[tex]v_{ave} = \frac{\Delta x}{\Delta t}[/tex]

[tex]\Delta t = t_f - t_i[/tex]

[tex]\Delta t = 4.00 s - 1.50s[/tex]

[tex]\Delta t = 2.50 s[/tex]

[tex]\Delta x = x_f - x_i[/tex]

[tex]\Delta x = 2m - 7m[/tex]

[tex]\Delta x = -5m[/tex]

[tex]v_{ave} = \frac{-5m}{2.50s}[/tex]

[tex]v_{ave} = -2m/s[/tex]

So after that was done I went on to part (b) which first asked to find the slope of the tangent point was easily done by:

[tex]m = \frac{y_2 - y_1}{x_2 - x_1}[/tex]

[tex]m = \frac{0 - 12}{4 - 0}[/tex]

[tex]m = \frac{-3}{1}[/tex]

Now I am completely stumped as to what they're asking for how to Determine the instantaneous Velocity at t = 2.00 s and Don't get me started on (c). Oh an p.s. Hey I'm new to PF ;p!

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