Finding Velocity via Convervation of Energy

  • Thread starter Norngpinky
  • Start date
  • #1
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Homework Statement


A projectile is shot upward from the top of a cliff in an angle of 25 with a velocity of 195 m/s.The height of the cliff is 315m. What will be its speed when it strikes the ground below? (Use conservation of energy)



Homework Equations


Ok...initial energy = final energy

Initial energy = .5m*(initial velocity square) + mgy
Final energy = .5m*(final velocity square)

initial velocity = sin*theta*upward initial velocity = sin25*195


The Attempt at a Solution



So I set them to equal and I got final V to be 114, but it says I had it wrong, canceling out the mass.... I have no clue what I did wrong there...
 

Answers and Replies

  • #2
Delphi51
Homework Helper
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initial velocity = sin*theta*upward initial velocity = sin25*195
should not be used in this one. It is an energy problem, not a 2D motion analysis. Just use the 195 in the first 1/2m*v^2.
 
  • #3
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should not be used in this one. It is an energy problem, not a 2D motion analysis. Just use the 195 in the first 1/2m*v^2.
OK, thank you! =)
 

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