Thursday, December 14, 2006

Myth: Bullets fly so fast that they are unaffected by gravity.

This is one of the n topics (why do we have 2 eyes, gravity, speed etc..,) we discussed yesterday.. so boys had to say that gravity does not effect a bullet fired from a gun, because the speed is so high that gravity does not act on it.. so the bullet travels horizontally.. (does this mean it escaped the gravitational force?).. but

the fact..

A bullet is a projectile and as such, its horizontal motion is unrelated to its vertical motion. Just because it is moving rapidly in the horizontal direction does not mean that it will fall any slower than an object that is not moving horizontally. They still fall with the acceleration due to gravity
(). (source)

Here is a excellent example given by Joy Wagon... The Monkey and the Gun

We can't see the fall of a bullet because it happens so quickly that your eye cannot catch it. The trajectory from the point where the bullet comes out of muzzle and the point it hits the target is not horizontal but a curve (practice makes your brain calculate this gravitational pull, similar to a ball you throw to hit a target).. so what is it all proportional to ? is it time??

Here is a experiment conducted by B.E. Spencer... A Closer Look at Trajectories

Newton's first law says that the bullet will continue to travel on a straight line forever if no forces act upon it. But the bullet falls, so there is a pull and it is gravitational force which is pulling it..

So.. when you get to shoot something.. make sure you keep in mind that gravitational force acts on the bullet and shoot accordingly..

Updated after the first comment :)

Sights on guns are used to adjust for the effects of gravity on a bullet. When you set the sights on a gun, you must set them for the range you are likely to be shooting from. Basically what you are doing is adjusting the "Line from sights" to cross the "Bullet path" at the distance you will likely be shooting from. Beyond this length, your bullet will hit low, closer than this length, your bullet will hit high. This also only sets your gun correctly for level ground. If you shoot down from a hill, your bullet will hit high or if you shoot up a hill (dangerous practice) your bullet will hit low.


Anonymous said...

Thats why you shouldn't be sleeping when we discuss :)

We never said that bullets wouldn't be affected by gravity, we said that the impact of gravity on a bullet was negligible and you dont have to keep gravity in mind while shooting.

Santosh S Kumar said...

Ragi.. read the last para.. which I just updated.. it says..

"Sights on guns are used to adjust for the effects of gravity on a bullet."

which does mean that the gravity is not negligible..

The laser is adjusted by taking the gravity into consideration..