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2D Kinematics

  • Thread starter DocDot
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Im sorry I just realized this is in the wrong subforum......

Homework Statement



Hello Everyone! Im new here and am having trouble with this webassign question. I was able to work out the answer to the first two but the last two are giving me trouble. Im not sure if this is right subforum to put this in, but I am in physics with calculus (Mechanics).

A boy throws a stone horizontally from the top of a cliff of height h toward the ocean below. The stone strikes the ocean at distance d from the base of the cliff. In terms of h, d, and g, find expressions for the following.

the time t at which the stone lands in the ocean

the initial speed of the stone

the speed of the stone immediately before it reaches the ocean

the direction of the stone's velocity immediately before it reaches the ocean

Homework Equations



vf=vi+gt
xf=xi+vi(t)+(g/2)(t^2)

The Attempt at a Solution



The answer I got for the first one was √(h/(g/2)) which was right

The second one I got was √((d^2)/(h/(g/2))) which was also right

For the third one I got vf=g(√(h/(g/2))) which I thought was right because vf for the x componet is 0 and the velocity is maximum at tf, however webassign is telling me im wrong.

Thank you all for the help in advance!!!!
 
Last edited:

Answers and Replies

  • #2
lewando
Homework Helper
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If you show your steps leading to your result, the mistake can be better identified.
 
  • #3
PhanthomJay
Science Advisor
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...vf for the x component is 0 ...
Think about this a bit more....what is vf_x just before it hits the ocean?
 

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