Question

How to get spring constant (k) in projectile,
only given:
θ=45°
range = 1.37 m
t= 0.56 s
Vi= 3.46 m/s
Vf= 4.63 m/s
hints: Potential Energy, Kinetic Energy, Elastic Potential Energy.

Answer 1

PE = mgh
F = -kx
KE = (1/2)mv^2

Answer 2

any idea? xDD
please help. :)

Answer 3

Draw free body digram (FBD)