Projectile Range Comparison


Can you answer this question?
Two projectiles are launched from ground level at the same angle above the horizontal, and both return to ground level. Projectile A has a launch speed that of projectile B. Assuming that air resistance is absent, what should be the ratio of the ranges?


I think your question is missing some data. If you intend that projectile A has twice the launch velocity as B but otherwise identical, you might think of it like this. The horizontal and vertical component of the faster projectile are both doubled ( in the scenario I have set up). Assuming that neither go far enough that the Earth's curvature has to be considered, the height to which each projectile will rise is m*g*h=1/2*m*vh2 - conservation of energy. Since vhA is twice vhB, vhA2 is 4 times vhB2 so hA=4*hB

The time required for A to come down is given by 4*h=1/2*a*tA2. The time for the B to fall from its peak is given by h=1/2*a*tB2. Dividing these equations we get 4=tA2/tB2. Taking the square root we get 2=tA/tB or tA=2*tB. Of course the rise time will equal the fall time so the relationship of total times in the air will be the same. Since A is in the air 2 times as long as B and its horizontal velocity is twice as much, A will go 4 times as far as B.