- #1

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## Homework Statement

A particle moves in a plane. The particle (x,y) position on the plane is given by:

[tex]x = -34t^4 − 28t^3 + 7[/tex]

[tex]y = 25t^2 + 13t^3 + 5[/tex]

Therefore the particle's displacement [from the (x,y) origin) at time t = 68 s is

[tex](736000000m) i + (4200000m)j[/tex]

**(a)**What is the particle's velocity at 68 s ?

**(b)**What is the particle's acceleration at 68 s ?

## The Attempt at a Solution

(a) for this part the correct answer has to be

[tex]v_p = (43200000m) i + (184000m)j[/tex]

But I can't see how they have arrived at this answer! The velocity is [tex]\frac{\Delta x}{\Delta t}[/tex]

[tex]\Delta t = t_f-t_i=68-0 =68[/tex]

[tex]\Delta x = x_f-x_i = 736000000 - 7 = 375999993[/tex]

So, [tex]\frac{375999993}{68}=10823529.31[/tex].

This is not the right answer for the i component. What is the problem?