A girl throws a rock horizontally, with a velocity of 10 m/ s, from a bridge. It falls 20 m to the water below. How far does the rock travel horizontally before striking the water?

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Answer 1 · 2015-11-07T23:21:22

#20.2"m"#

You use the vertical component of the motion to get the time of flight:

#s=1/2"g"t^2#

#:.t=sqrt((2s)/(g))#

#t=sqrt((2xx20)/(9.8))#

#t=2.02"s"#

Now we use the fact that the horizontal component of velocity is constant so:

#s=vxxt#

#:.s=10xx2.02=20.2"m"#