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 12 m/s and the second part of mass 2 kg moves with second part of mass 2 kg moves with 8 m/s speed. If the third part flies off with 4 m/s speed, then its mass is, from Physics Laws of Motion Class 11 Manipur Board
Zigya Logo

Chapter Chosen

Laws of Motion

Book Chosen

Physics Part I

Subject Chosen

Physics

Book Store

Download books and chapters from book store.
Currently only available for.
CBSE Gujarat Board Haryana Board

Previous Year Papers

Download the PDF Question Papers Free for off line practice and view the Solutions online.
Currently only available for.
Class 10 Class 12

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 12 m/s and the second part of mass 2 kg moves with second part of mass 2 kg moves with 8 m/s speed. If the third part flies off with 4 m/s speed, then its mass is,

  • 3 kg

  • 5 kg

  • 7 kg

  • 17 kg


B.

5 kg

We have,

p1 + p2 + p3 = 0 [ because p = mv]

Therefore,

1 x 12 i  + 2 x 8 j + p3 = 0

rightwards double arrow space 12 space straight i space plus space 16 space straight j space plus space straight p subscript 3 space equals space 0

rightwards double arrow space straight p subscript 3 space equals space minus left parenthesis 12 space straight i space space plus space 16 space straight j right parenthesis

therefore space straight p subscript 3 space equals space square root of left parenthesis 12 right parenthesis squared plus left parenthesis 16 right parenthesis squared end root

space space space space space space space space space space equals space square root of 144 space plus space 256 space end root

space space space space space space space space space space equals space 20 space kg minus straight m divided by straight s

Now. p3 = m3 v3

This implies,


straight m subscript 3 space equals space straight p subscript 3 over straight v subscript 3 space
space space space space space equals space 20 over 4 space
space space space space space equals space 5 space kg

We have,

p1 + p2 + p3 = 0 [ because p = mv]

Therefore,

1 x 12 i  + 2 x 8 j + p3 = 0

rightwards double arrow space 12 space straight i space plus space 16 space straight j space plus space straight p subscript 3 space equals space 0

rightwards double arrow space straight p subscript 3 space equals space minus left parenthesis 12 space straight i space space plus space 16 space straight j right parenthesis

therefore space straight p subscript 3 space equals space square root of left parenthesis 12 right parenthesis squared plus left parenthesis 16 right parenthesis squared end root

space space space space space space space space space space equals space square root of 144 space plus space 256 space end root

space space space space space space space space space space equals space 20 space kg minus straight m divided by straight s

Now. p3 = m3 v3

This implies,


straight m subscript 3 space equals space straight p subscript 3 over straight v subscript 3 space
space space space space space equals space 20 over 4 space
space space space space space equals space 5 space kg
2449 Views

What is Aristotle’s law of motion?

Aristotle’s law of motion states that an external force is required to keep the body in motion.
2445 Views

When the branches of an apple tree are shaken, the apples fall down. Why?

The apple fall from an apple tree when it shaken because of inertia of rest. Apple is in a state of rest and when the tree is suddenly shaken, apples still tends to remain in it's same state of rest whereas branches move. 

So, the apples fall down. 
1475 Views

Is Aristotle’s law of motion now correct?

No. Aristotl'e law of motion is false. 
1233 Views

State Galileo’s law of motion.

Galileo’s law of motion states that, a body continues to move in the same direction with constant speed, if no force is acting on the body. 
1332 Views

Define inertia.

The property by virtue of which the body cannot change its state of rest or uniform motion in a straight line, unless an external force is acting on the body is called as Inertia. 
1316 Views