Physics Help Forum Time is not working out

 Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

 Sep 27th 2010, 05:54 PM #1 Member   Join Date: Nov 2009 Posts: 94 Time is not working out Hey There, A golf ball rolls off a horizontal cliff with an Vo speed of 11.4 m/s. The ball falls a vertical distance of 15.5 m into a lake below. It asks a) how much time does the ball spend in the air b) what is the speed v of the ball just before it strikes the water? I solved for B the V as 20.82 m/s.w I got Vo = -11.4, d = -15.5 m, a= -9.8 m/ss. I tried every way to get time of 1.78 s using all formulas that I can and for some reason I am coming up short in time. What am I doing wrong. Just pluncking the numbers and nothing. HELP? Tks
Sep 28th 2010, 12:04 AM   #2
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 Originally Posted by bradycat Hey There, A golf ball rolls off a horizontal cliff with an Vo speed of 11.4 m/s. The ball falls a vertical distance of 15.5 m into a lake below. It asks a) how much time does the ball spend in the air b) what is the speed v of the ball just before it strikes the water? I solved for B the V as 20.82 m/s.w I got Vo = -11.4, d = -15.5 m, a= -9.8 m/ss. I tried every way to get time of 1.78 s using all formulas that I can and for some reason I am coming up short in time. What am I doing wrong. Just pluncking the numbers and nothing. HELP? Tks
Vo = 11.4 m/s is in the horizontal direction.The vertical component of the initial velocity is zero.

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