# Projectile Motion

 P: 26 1. The problem statement, all variables and given/known data A projectile is launched with a speed of 40 m/s at an angle of 60 degrees above the horizontal. Use conservation of energy to find the maximum height reached by the projectile during its flight. 2. Relevant equations KEi+PEi=KEf+PEf 3. The attempt at a solution i am not sure where vf would come from. Would it be just Vi*cos(60)? I am not sure why that makes sense. Does Vix=Vf?...and why?
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P: 5,341
 Quote by wowdusk 1. The problem statement, all variables and given/known data A projectile is launched with a speed of 40 m/s at an angle of 60 degrees above the horizontal. Use conservation of energy to find the maximum height reached by the projectile during its flight. 2. Relevant equations KEi+PEi=KEf+PEf 3. The attempt at a solution i am not sure where vf would come from. Would it be just Vi*cos(60)? I am not sure why that makes sense. Does Vix=Vf?...and why?
Assume your potential energy is 0 when you launch and your kinetic energy in the y direction is what? 1/2*m*Viy2?

And at the height it has no vertical kinetic energy and the potential energy is what?

What is the vertical component of V? (Hint: it's not Vi*cos(60))
 P: 26 why do i need the vertical component of Vi I dont know how to find the V at the heighest point... At the heighest point is the V in vertical direction 0 anyway?
 P: 26 Projectile Motion I think i solved this out...i got 61m???
HW Helper
P: 5,341
 Quote by wowdusk why do i need the vertical component of Vi I dont know how to find the V at the heighest point... At the heighest point is the V in vertical direction 0 anyway?
Yes your final V is 0.

But your initial V is the vertical component of V, as that is the component of V that is affected by gravity ... you know, where that potential energy is building.
 P: 26 Thank you...can you check if my answer is right?

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