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Laws of Motion

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Physics Part I

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Physics

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12

A shell of mass 200 g is ejected from a gun of mass 4 g by an explosion that generates 1.05 kJ of energy. The initial velocity of the shell is

  • 100 ms-1

  • 80 ms-1

  • 40 ms-1

  • 120 ms-1


A.

100 ms-1

In the given problem conservation of linear momentum and energy hold good.
Conservation of momentum yields.

m1v1 + m2v2 = 0
4v1 + 0.2 v2  = 0

Conservation of energy yields


1 half straight m subscript 1 straight v subscript 1 squared space plus 1 half space straight m subscript 2 straight v subscript 2 squared space equals space 1050 space space space... left parenthesis straight i right parenthesis
or
1 half space straight x 4 straight v subscript 1 squared space plus space 1 half 0.1 straight v subscript 2 squared space equals space 1050 space space space.... space left parenthesis ii right parenthesis

solving space eqs. space left parenthesis straight i right parenthesis space and space left parenthesis ii right parenthesis space we space have
straight v subscript 1 space equals space 100 space straight m divided by straight s

In the given problem conservation of linear momentum and energy hold good.
Conservation of momentum yields.

m1v1 + m2v2 = 0
4v1 + 0.2 v2  = 0

Conservation of energy yields


1 half straight m subscript 1 straight v subscript 1 squared space plus 1 half space straight m subscript 2 straight v subscript 2 squared space equals space 1050 space space space... left parenthesis straight i right parenthesis
or
1 half space straight x 4 straight v subscript 1 squared space plus space 1 half 0.1 straight v subscript 2 squared space equals space 1050 space space space.... space left parenthesis ii right parenthesis

solving space eqs. space left parenthesis straight i right parenthesis space and space left parenthesis ii right parenthesis space we space have
straight v subscript 1 space equals space 100 space straight m divided by straight s

1205 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

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

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

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

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