A 14.3-g bullet is fired into a 5.21 kg block of wood. The block is attached to a spring that has a spring force constant of 450 N/m. The block and bullet continue to move, compressing the spring by 22.0 cm before the whole system momentarily comes to a stop. The coefficient of kinetic friction between block and the surface on which the block is resting is 0.35. Determine the initial speed of bullet.

Answer :

xero099

Answer:

The initial speed of the bullet is [tex]v_{o} = 889.199\,\frac{m}{s}[/tex].

Explanation:

The collision between bullet and block is inelastic and let suppose that motion occurs on a horizontal surface, so that changes in gravitational potential energy can be neglected. Initially, the intial speed of the bullet-block system can be determined with the help of the Work-Energy Theorem and the Principle of Energy Conservation:

[tex]K = U_{k} + W_{loss}[/tex]

[tex]\frac{1}{2}\cdot (5.224\,kg)\cdot v^{2} = \frac{1}{2}\cdot \left(450\,\frac{N}{m}\right)\cdot (0.22\,m)^{2} + (0.35)\cdot (5.224\,kg)\cdot \left(9.807\,\frac{m}{s^{2}} \right) \cdot (0.22\,m)[/tex]

The initial speed of the bullet-block system is:

[tex]v \approx 2.383\,\frac{m}{s}[/tex]

Now, the initial speed of the bullet is determined by applying the Principle of Momentum Conservation:

[tex](0.014\,kg)\cdot v_{o} = (5.224\,kg)\cdot \left(2.383\,\frac{m}{s} \right)[/tex]

[tex]v_{o} = 889.199\,\frac{m}{s}[/tex]

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