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"#