Question

In an ballistics demonstration a police officer fires a bullet of mass 50.0g with speed 200m/s on soft plywood of thickness 2.00cm.the bullet emerges with only 10% of its initial kinetic energy. what is the emergent speed of the bullet?​

Answer 1

1/2 mv2 =0.1(KE)

=0.1 1/2 mu 2

1/2 ×50×10 −3 u 2 =0.1×[ 1/2 ×50×10 −3 ×20 2 ]

u 2 =0.1×200 2

u=20 ✓10

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Answer 2

Answer:

Given:

m=50 g, u=200 m/s, t=2 cm

InitialKE=

2

1

mu

2

=

2

1

×

1000

50

×400×10

2

=1000 kg−m/s

2

FinalKE=

10

1

(InitialKE)=

10

1

×1000=100 kg−m/s

2

∴

2

1

mv

2

=100⟶

2

1

×

1000

50

v

2

=100

v

2

=40×100⟶v=20

10

m/s

Explanation:

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