Kinematics. Urgent yes or now answer!

  • Thread starter ryan8642
  • Start date
  • #1
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Homework Statement


1. an object is thrown vertically up from a window that is 3.6m above the ground.
Its initial speed is 2.8m/s.


Homework Equations


N/a


The Attempt at a Solution



Is the time the object takes to ascend equal to the amount of time it takes to descend?
 

Answers and Replies

  • #2
125
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The acceleration of the oobject will be g down.
now you can calculate the time spent to go up, because v0 = g*t
the height travelled up: h=v0*t - 1/2*g*t^2
now down: h+h0 = 1/2*g*t^2

To look at it in a graphical way:
draw a parabola upside down. x coordinate is the time, y is the height, the steepnes of the parabola is the speed. Move the parabola such that
- it is raising at x=0 : the initial speed is positive
- it is positive at x=0: initially it is in up in the window

Now note whether the y distance of the top of the parabola form the origo (time spent up) is equivalent to the y distance from the top of the parabola to where it cuts the horizontal axis (time spent down).
 

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