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A 0.0124-kg bullet is fired horizontally into a 3.63-kg wooden block attached to

ID: 1649995 • Letter: A

Question

A 0.0124-kg bullet is fired horizontally into a 3.63-kg wooden block attached to one end of a massless, horizontal spring (k = 876 N/m). The other end of the spring is fixed in place, and the spring is unstrained initially. The block rests on a horizontal, frictionless surface. The bullet strikes the block perpendicularly and quickly comes to a halt within it. As a result of this completely inelastic collision, the spring is compressed along its axis and causes the block/bullet to oscillate with an amplitude of 0.261 m. What is the speed of the bullet?

Explanation / Answer

From the given question,

mass of bullet(m)=0.0124 kg

mass of wooden block(M)=3.63 kg

spring constant(k)=876 N/m

amplitude of oscillation(x)=0.261 m

initial speed of bullet=v

Final speed of bullet-wood system=V

by conservation of momentum,

m(v)+ M(0)=(m+M)V

V=mv/(m+M)

By conservation of energy

(1/2)(m+M)V2=(1/2)(k)x2

(m+M)V2=(k)x2

(m+M)[mv/(m+M)]2=(k)x2

(m2v2)/(m+M)=kx2

v2=(kx2)(m+M)/m2

v2=(876*0..2612)(0.0124+3.63)/(0.0124)2

=1.4136*106

v=1188.95 m/s

Speed of bullet is 1190 m/s (Approx)