Free Fall/Constant Acceleration Problem

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


An object is launched upwards with a velocity of 25 m/s. At what time (or times) will the object be located twenty meters above the ground?


Homework Equations





The Attempt at a Solution


I started off with the following variable list:
Xo=0 Vo=25
X=0 V=0
t=? a=-9.8
Which seems very off to me.
When trying to solve I got 2.55 seconds. But is there another time where it reaches 20m?
How do you solve this?
Thanks!

[tex]x=V_0 t-\frac{1}{2}gt^2[/tex]


will help you. Remember it is going up, reaching maximum height and falling back down to the ground. So at two times it will be 20m up in the air.

Would my answers be 0.994sec and 1.557sec?

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #2
Delphi51
Homework Helper
3,407
11
I got one of those answers but not the other!
Maybe you should show your work, in particular the quadratic equation so we can see what your a, b and c numbers are for entry into the quadratic formula.
 

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