# Initial velocity required depend on the mass of projectile

1. Jan 17, 2004

### techno

Does the Initial velocity required depend on the mass of projectile to impart a projectile of perticilar angle and perticular height?

2. Jan 17, 2004

### LURCH

No, balistic trajectories do not depend on mass. A balistic trajectory is the course a projactile takes as its momentum is balanced against gravity, and gravity accelerates all freefalling objects at pretty much the same rate. So the forward speed of a projectile determines how far it will travel in the amount of time it takes to fall to the ground, the that amount of time is the same for heavy or light things. In fact, a balistic trjectory is a segmant of an orbit.

All this is neglecting any differences in wind resistance, of course.

Now, if one wanted to get really picky, I suppose it can be said that more massive objects do fall a tiny bit faster than lighter objects because, all though the Earth's gravitationl pull on both objects is the same, the heavier object has a stronger pull on the Earth. But that would be silly.

3. Jan 17, 2004

### HallsofIvy

Staff Emeritus
It would be not only both silly and picky, it would be incorrect. Neglecting air resistance, the rate at which an object and the earth accelerate toward each other is independent of the mass of the object.