Posted by Jackie on Tuesday, April 6, 2010 at 12:19am.
c. use kinematics equation
y=vi*t+1/2at^2
vi= 0 (because rock was dropped)
a=-9.8m/s^2
t= 4s (time given)
plug in and you get your height
a. use kinematics equation
vf^2=vi^2+2ay
vi=0 (rock dropped)
a=-9.8
y= (whatever you got from part c)
plug in and solve
b. ?
To do this problem you just need to use a few simple equations:
V = V0 + at
X = X0 + V0*t + .5*a*(t^2)
and
V^2 = V0^2 + 2*a*(X - X0)
where V0 equals the initial velocity
X0 equals the initial height
t equals the time
a is just the acceleration (gravity in this case [9.81 m/s^2])
V is the final velocity
X is the final height
I think this should help you.
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