A rifle is fired and recoils when the bullet leaves the gun. This is an example of Newton's third law. The acceleration of the bullet is

Question

anonymous · Answer

I know that to find acceleration is final velocity - initial velocity divided by change in time. But I don't see anything that relates?

plainntall · Answer

Remember Newton's 3rd law says the Force is equal, but oppositely directed or
Force on the rifle = -Force on the bullet
If m is the mass of the bullet and a is the acceleration of the bullet how would you express the acceleration of the bullet in terms of the force on the rifle and the mass of the bullet?

anonymous · Answer

Im still confused?

anonymous · Answer

Would the acceleration of the bullet be smaller than that of the rifle?

plainntall · Answer

I think they want you to make a statement about the acceleration of the bullet in terms of the force acting on the gun and the mass of the bullet.
If M=mass of rifle, A=acceleration of rifle
m=mass of bullet, a = acceleration of bullet
Newton's Second and Third law give you
MA=-ma
a=-MA/m which means the acceleration of the bullet is in the opposite direction of the acceleration of the rifle and equal to MA/m.

plainntall · Answer

I would say yes, the acceleration of the bullet would be a lot more than the acceleration of the rifle because the Mass of the rifle is much bigger than the mass of the bullet.

anonymous · Answer

What they gave me as the possible answers are:

• The same as that of the rifle.
• Greater than that of the rifle.
• Smaller than that of the rifle.

plainntall · Answer

well if the force is the same, but oppositely directed and the mass of the bullet is less than the mass of the rifle, what happens to the acceleration?
a=F/m ; the acceleration of the bullet has to be greater as you said correct?

anonymous · Answer

That is correct, But with the same question stated above they are also looking for the force on the bullet instead of looking for the acceleration?