A stone is thrown directly upward with a speed of 30m/s. What is its velocity 4s later? Assume for convenience that g=10m/s2.

+2 votes

 

1. 30m/s, upward
2. 30m/s, downward
3. 10m/s, upward
4. 10m/s, downward
5. 70m/s upward
6. 70m/s, downward
asked Dec 11, 2012 in Physics by Zeka22 ~Expert~ (357 points)
    

1 Answer

0 votes

Use the formula for velocity:

vf= vi + a(tf − ti)

therefore:

vf = +30m/s +(-10m/s^2)(4s-0s)

therfore vf = -10m/s

4. 10m/s, downward

 

answered Dec 11, 2012 by Luffy ~Expert~ (977 points)

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