Bullet and block (1 Viewer)

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

a rifle fires a(n) 6g bullet with a muzzle velocity of 390m/s into a block of wood. the bullet comes to rest after it has made a(n) 18cm deep hole in the wood. what is the magnitude of the average frictional force slowed the bullet?

can i use this formula?

Doc Al

You could, but you'd first have to figure out the time. Instead, consider the work done by the frictional force on the bullet.


Science Advisor
Homework Helper
What would you use for the time?

I suggest asking yourself how much work the frictional force does.
is it W=Kf-Ko ?
yes, but make sure not to forget that the work done by friction will be negative.
so.....W=1/2mVf^2-1/2mVo^2 does Vf cancel since it comes to rest?
yes, it does
the answer is W=456.3 is that all?
you've found the work, but the question wants to know the force. so what is the equation for work?
is it W=Fd
yes, that's right
Thank You So Much!!!!!!

The Physics Forums Way

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving