Projectile Motion and maximum height

AI Thread Summary
A projectile launched at 40 m/s and 60 degrees requires the use of conservation of energy to determine its maximum height. The initial kinetic energy and potential energy are converted to potential energy at the peak, where vertical velocity is zero. The vertical component of the initial velocity is crucial for calculating the height, as it is affected by gravity. The discussion clarifies that the vertical component is not simply Vi*cos(60) and emphasizes the importance of identifying the correct initial vertical velocity. The calculated maximum height reached by the projectile is 61 meters.
wowdusk
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Homework Statement


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.

Homework Equations


KEi+PEi=KEf+PEf

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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wowdusk said:

Homework Statement


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.

Homework Equations


KEi+PEi=KEf+PEf

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))
 
why do i need the vertical component of Vi

I don't know how to find the V at the heighest point...

At the heighest point is the V in vertical direction 0 anyway?
 
I think i solved this out...i got 61m?
 
wowdusk said:
why do i need the vertical component of Vi

I don't 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.
 
Thank you...can you check if my answer is right?
 

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