A projectile is shot vertically upward with a given initial velocity. It reaches a maximum height of 100 m. If, on a second shot, the initial velocity is doubled then the projectile will reach a maximum height of ____________?

Answer 1

initially, all the energy is KE = 1/2 mv^2

At the peak, all the KE has become PE = mgh

So, with 2v at first, there's 4 times the KE. That means 4 times the height at the peak.