Newton's 3rd law question -- A gun firing a bullet

[samcoelho]

Homework Statement

A 10.0 kg gun applies a force of 250 N left on a 0.0200 kg bullet. What is the force on the gun?

Relevant Equations

F=ma

I'm confused by which forces should be equal to each other and what I solve for. How should I approach this problem?

 

[Delta2]

well the data of the problem (we can ignore the given masses for the purpose of answering the question posed by the problem) can be summarized as follows:

The force from the gun to the bullet is equal to 250N and towards the left.

Using Newton's 3rd law you should be able to complete the following sentence
The force from the bullet to the gun is equal to ... and towards the ...

 

[Delta2]

You basically have two bodies (the gun and the bullet) which interact. The gun applies a force to the bullet, hence by Newtons 3rd law, the bullet applies an equal and opposite force to the gun.

I know it might seem counter intuitive to you that the tiny bullet applies a force to the gun, but that is what Newton's 3rd law tell us and this is pretty much what is happening in reality if we omit some details (the details are that the gun and the bullet interact through the gas mixture produced by the ignited gunpowder which has a Pressure and a Temperature, but we can omit these details for now).