Posted by sachin on .
A 10G bullet is short from a 5kg gun with a velocity of 400m/s.What is the speed of recoil of the gun?

Physics? Math? What? 
Writeacher,
Please type your subject in the School Subject box. Any other words, including obscure abbreviations, are likely to delay responses from a teacher who knows that subject well.

physics 
MathMate,
Initial momentum = 0
momentum of bullet = mv
momentum of gun = MV
Using conservation of momentum
mv+MV = 0
therefore
V=mv/M 
physics 
drwls,
The momenta of the bullet and the gun are equal (and opposite in direction) after firing. If Vr is the recoil velocity,
5.0*Vr = 0.01 * 400
Solve for Vr, which will be im m/s.
Note that I had to use the same mass units for bullet and gun.