# Calculate the average net force acting on the bullet

#### silje

I have a physics problem and are woundering if someone can please help me! Here's the problem: A bullet of mass 20 g strikes a fixed block of wood at a speed of 320 m/s. The bullet embeds itself in the block of wood, penetrating to a depth of 6.0 cm. Calculate the average net force acting on the bullet while it is being brought to rest. (1.7 x 14^4 N)

would have been nice with the whole calculation.
Thanks! :!!)

Related Introductory Physics Homework Help News on Phys.org

#### PhanthomJay

Homework Helper
Gold Member
silje said:
I have a physics problem and are woundering if someone can please help me! Here's the problem: A bullet of mass 20 g strikes a fixed block of wood at a speed of 320 m/s. The bullet embeds itself in the block of wood, penetrating to a depth of 6.0 cm. Calculate the average net force acting on the bullet while it is being brought to rest. (1.7 x 14^4 N)

would have been nice with the whole calculation.
Thanks! :!!)
Trythe work-energy theorem, which states
$$W_{net} = \Delta KE$$
What is the initial kinetic energy of the bullet just before it penetrates the wood? What is its final kinetic energy when it comes to a stop in the wood? What is the difference between the two energies? What is the definition of work?

#### JonnyA42

Alternatively, you can use kinematics to determine the acceleration of the bullet (vf^2 = vi^2 + 2ad), then use Newton's 2nd Law to determine the force (F = ma).

#### silje

thank you very much! =)