Question #4ff5f

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Answer 1 · 2017-04-03T21:29:01

$"please look at below."$

a)

enter image source here

b)

$"given :"$
$v_i:"initial velocity of rock ; "v_i=15" "m/s$
$h:?$
$t:?$

c)

$"acceleration is g=-9.81 "m/s^2" (upward) and g=+9.81 "m/s^2 " (downward)"$

d)

$h=v_i*t-1/2*g*t^2$

$"plug t=1 "$

$h=15*1-1/2*9.81*1^2$

$h=15-4.905$

$h=10.095" meters"$

e)

$v=v_i-g*t$

$"plug "v=3 ,v_i=15$

$3=15-9.81*t$

$9.81 t=15-3$

$9.81t=12$

$t=12/(9.81)$

$t=1.22 "sec"$

f)

$-5=15-9.81*t$

$9.81t=15+5$

$9.81t=20$

$t=20/(9.81)$

$t=2.04 " sec"$