Calculating Impulse and Work on a Bullet

[Spaniard]

Homework Statement

A bullet of mass 0.010 kg and speed of 100 m/s is brought to rest in a wooden block after penetrating a distance of 0.10 m. This process takes 0.02 seconds. Theblock remains stationary during this process.

a. what is the magnitude of the impulse delivered to the bullet by the block during this time?

b. How much work was done ont he bullet during this process?

Homework Equations

thats what I am wondering

The Attempt at a Solution

i can't find the formula to try it, i am pretty much just looking for the formula and what each thing stand for etc. Thanks

 

[RoryP]

Try using Ft=Δ(mv)

 

[Spaniard]

sorry sounds dumb but what does F,t, delta, and mv stand for?

 

[RoryP]

no that's a perfectly decent question! if you have never come across this equation you can't be expected to know what it means!
F= force
t= time
delta= change in
m= mass
v= velocity
just a note, the product Ft is known as impulse =]

 

[Spaniard]

ok so i have the change in velocity, and time, but the problem says nothing about the change of mass. and don't have the force so I am assuming there's a separate formula involving how much the bullet penetrated that will give me the force or change of mass but I am thinking force. Anyone know what formula i hsould use or where i go from here? thanks

 

[RoryP]

note that Ft=Δ(mv)
mv is just the bullet's momentum, for the momentum to change you don't necessarily have to change the mass

 

[Spaniard]

whats the unit measure for impulse? Btw it all makes sense now. Thanks

 

[RoryP]

Ns or kgms^-1
what was the answer then?? just to check if i got it right as well =]