Physics Problem Help!!?

Question

I have a problem that says:

If you jump upward with initial speed 4.0 m/s, how high will you go?

I'm not sure which formula to use, if I have to use one at all. Does anybody know how to get the answer?! [:

Answer 1

id use v=vo + at

0m/s=4.0m/s - 9.8t

t=2.45 s                               --> 2.5s if ur using significant figures

after finding time up you could do this...(i'll use an alternate strategy than the one most people would use)

v(avg)=(vi+vf)/2  and  v=d/t

v(avg)=(4.0m/s + 0m/s)/2=2.0m/s

then  v(avg.)=d(the distance up)/t(time up)

        2m/s=d/2.45s

        d=4.9m

hope this alternate method could help.

Answer 2

use:

vf^2=v0^2+2ad

vf=final velocity = 0 here since at the peak of your motion your vertical speed is zero

v0=initial speed =+4m/s (plus because we set up as the positive direction)

a=accel = -9.8 m/s/s (accel due to gravity, note neg sign)

d=distance to be solved for,

so:

0^2=4^2-2x9.8xd

d=16/19.6=0.82 m