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QNEET-2016-Ph-1148: NEET 2016 Physics - Class 11 NEET-2016-Ph-1148 Solution: A bullet of mass 10 g moving horizontally with a velocity of…
A bullet of mass 10 g moving horizontally with a velocity of strikes a wood block of mass 2 kg which is suspended by light inextensible string of length 5 m. As a result the centre of gravity of the block found to rise a vertical distance of 10 cm. The speed of the bullet after it emerges out horizontally from the block will be
Multiple Choice Options
- A 100 m s _ 1
- B 80 m s _ 1
- C 120 m s _ 1
- D 160 m s _ 1
Step-by-Step Verified Solution
Mass of bullet, m = 10 g = 0.01 kg
Initial speed of bullet, u = 400 m s �1
Mass of block, M = 2 kg
Length of string, l = 5 m
Speed of the block after collision = v1
Speed of the bullet on emerging from block, v = ?
Using energy conservation principle for the block,
(KE + PE) Reference = (KE + PE) h
_ 1 2 M v 1 2 = M g h o r , v 1 = 2 g h
v 1 = 2 _ 10 _ 0.1 = 2 m s _ 1
Using momentum conservation principle for block
and bullet system,
(M _ 0 + mu) Before collision = (M _ v 1 + mv) After collision
_ 0.01 _ 400 = 2 2 + 0.01 _ v
_ v = 4 _ 2 2 0.01 = 117.15 m s _ 1 � 120 m s _ 1