Question

A bullet having q nass of 10g and moving with a speed of 1.5 m/s ,penetrades a thick wooden plank of mass 900g . The plank was initialy at rest . The bullet gets embedded in the plank and both move together . Determine their velocity.

Answer 1

data:m1=10g=10×10-3
u(initial velocity)=1.5m/s,m2=0m/s
therefore, V1=V2=??
by the law of conservation of momentum
m1u1+m2u2=m1u1+m2u2
as u(initial velocity)=0m/s and v1=v2=v1
we have m1u1=(m1u2)v
there fore V=m1v1
m1+m2
= 10×10-3×1.5
10×10-3+90×90-3
=10×1.5m/s=0.15m/s
100
therefore the speed with which the plank containing the bullet moves =0.15m/s