Does Newtons 3rd law mean that half of the energy is wasted?

812 viewsOtherPhysics

This may sound dumb to some folks, but lets say I fire a gun. 1000N of force goes into the bullet, and another 1000N of force goes into my body. Even if i strap the gun to the ground, it will just apply 1000N of force to move the earth by a tiny amount. Because of this, does it mean that it isn’t possible to have 2000N of force going to the bullet with the same parameters as before?

In: Physics

17 Answers

Anonymous 0 Comments

The energy generated by burning the gunpowder is indeed not 100% converted into accelerating the bullet (kinetic energy). No matter how hard you strap down the gun this will not change…

But by strapping down the gun you can change the proportion of kinetic energy that goes into the bullet in relation to how much of it goes into moving the gun.

Compare it to trying to push a block of concrete while standing on a slippery surface. When you try to push the block, you actually push yourself (or your feet) back.

Now because the bullet has less mass than the gun, it takes more energy to move the gun. Therefor the bullet is always going to accelerate faster than the gun. So strapping the gun down wont double the speed of the bullet.

You are viewing 1 out of 17 answers, click here to view all answers.