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QNEET-2013-Ph-1496: NEET 2013 Physics - Class 11 NEET-2013-Ph-1496 Solution: An explosion breaks a rock into three parts in a horizontal…
An explosion breaks a rock into three parts in a horizontal plane. Two of them go off at right angles to each other. The first part of mass 1 kg moves with a speed of and the second part of mass 2 kg moves with speed. If the third part flies off with speed then its mass is: 7 kg 17 kg 3 kg 5 kg
Multiple Choice Options
- A 7 kg
- B 17 kg
- C 3 kg
- D 5 kg
Step-by-Step Verified Solution
The situation is as shown in the figure.
According to law of conservation of linear momentum
p _ 1 + p _ 2 + p _ 3 = 0
_ p _ 3 = _ ( p _ 1 + p _ 2 )
Here, p _ 1 = ( 1 k g ) ( 12 m s _ 1 ) i ^ = 12 i ^ k g m s _ 1
p _ 2 = ( 2 k g ) ( 8 m s _ 1 ) j ^ = 16 i ^ k g m s _ 1
_ p _ 3 = _ ( 12 i ^ + 16 j ^ ) k g m s _ 1
The magnitude of p 3 is
p 3 = ( 12 ) 2 + ( 16 ) 2 = 20 k g m s _ 1
_ m 3 = p 3 v 3 = 20 k g m s _ 1 4 m s _ 1 = 5 k g