In a ballistics demonstration a police officer fires a bullet of mass 50.0 g with speed 200 ms^(-1) (see Table 6.2) on soft plywood of thickness 2.00 cm. The kinetic energy. What is the emergent speed of the bullet?

In a ballistics demonstration a police officer fires a bullet of mass

1.	In a ballistics demonstration a police officer fires a bullet of mass 50.0 g with speed 200 ms^(-1) (see Table 6.2) on soft plywood of thickness 2.00 cm. The kinetic energy. What is the emergent speed of the bullet?
Answer» Solution :The initial kinetic energy of the bullet is `mv^(2)"/"2= 1000 J`. It has final kinetic energy of `0.1xx1000= 100 J`. If `v_(F)` is the EMERGENT speed of the bullet, `(1)/(2) mv_(f)^(2)= 100 J` `v_(f)= sqrt((2xx100 J)/(0.05 kg))` `= 63.2 ms^(-1)`. The speed is reduced by approximately 68% (not 90%).