# Homework Help: Force vs. time

1. Apr 29, 2007

### leykis101

A projectile is fired with speed v at an angle with respect to the horizontal. Assume no air resistance. The projectile returns to the same level and it has a range R and altitude H.

Whats the impulsive force in the case of the projectile? what does the F vs. t for the projectile look like?

Last edited: Apr 30, 2007
2. Apr 29, 2007

### Xezlec

Can you be more specific? If you just mean an object in the air here on Earth, neglecting wind resistance, the force is always the same; gravity pulls down. Constantly. So... is the answer you want just "a flat line"? Surely you wanted more than that.

3. Apr 30, 2007

### KingNothing

Typically impulses are used with inelastic collisions, such as a projectile hitting another object and indenting it somewhat. For example, imagine dropping a golf ball into a bowl of sand.

Please be more specific as to which forces you are trying to calculate. If it is a homework problem, post the whole question.

4. May 1, 2007

### rcgldr

Assuming a flat earth here (R small compared to earth's radius). Speed v, and angle of initial launch can be determined from maximumum height H and range R.

The force depends on how long it takes to go from speed 0 to speed v and the mass of the projectile. The simplest case would be an idealistic constant force "cannon".