Free Fall 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!
 

Answers and Replies

  • #2
rock.freak667
Homework Helper
6,223
31

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.
 
  • #3
92
0
Would my answers be 0.994sec and 1.557sec?
 

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