Reasons for miscalculation of spring work and change in ke

[uknew]

can anyone help me in figuring out why i got different answers in my calculated value to my experiment value (or maybe its normal) when i calculated the approximate distance a projectile would shoot up when i compressed a spring thru a distance. i calculated the spring constant and found the final velocity of the projectile once in projectile motion(which would make it its initial as a projectile).i checked the distance it traveled vertcally.compred it to my calculated one and they were very different. can anyone help explain why?friction, weight of the spring were not considered.thank

 

[uknew]

also how does cutting the spring change the stiffness or av. forfce exerted. ?will it go higher or the same?any help is good

 

[Office_Shredder]

Hooke's law is under idealized conditions that you probably broke by compressing the spring as far as possible - at least this is a typical thing to do when shooting things up with springs. A full description of the setup and how you extracted the spring constant would allow us to better spot the problem

 

[uknew]

oh ok thanks