Finding Velocity via Convervation of Energy

[Norngpinky]

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...

 

[Delphi51]

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.

 

[Norngpinky]

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! =)