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Motion in Straight Line

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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

The force F acting on a particle of mass m is indicated by the force-time graph as shown below. The climate change in momentum of the particle over the time interval from zero to 8 s is,

  • 24 Ns

  • 20 Ns

  • 12 Ns

  • 6 Ns


C.

12 Ns

The area under F-t graph gives change in momentum.

For 0 to 2 s,

increment straight p subscript 1 space equals space 1 half straight x 2 straight x 6 space equals space 6 space kg minus straight m divided by straight s
For 2 to 4 sec,
increment straight p subscript 2 space equals space 2 space straight x space left parenthesis negative 3 right parenthesis space equals space minus 6 space kg minus straight m divided by straight s
For 4 to 8 sec,

increment straight p subscript 3 space equals space left parenthesis 4 right parenthesis straight x 3 space equals space plus 12 space kg minus straight m divided by straight s
So, total change in momentum for 0 to 8 sec is,

increment straight p subscript net space equals space increment straight p subscript 1 plus increment straight p subscript 2 plus increment straight p subscript 3

space space space space space space space space space space space equals left parenthesis plus 6 space minus 6 space plus 12 right parenthesis

space space space space space space space space space space space equals space 12 space kg minus straight m divided by straight s

space space space space space space space space space space space equals space 12 space Ns

The area under F-t graph gives change in momentum.

For 0 to 2 s,

increment straight p subscript 1 space equals space 1 half straight x 2 straight x 6 space equals space 6 space kg minus straight m divided by straight s
For 2 to 4 sec,
increment straight p subscript 2 space equals space 2 space straight x space left parenthesis negative 3 right parenthesis space equals space minus 6 space kg minus straight m divided by straight s
For 4 to 8 sec,

increment straight p subscript 3 space equals space left parenthesis 4 right parenthesis straight x 3 space equals space plus 12 space kg minus straight m divided by straight s
So, total change in momentum for 0 to 8 sec is,

increment straight p subscript net space equals space increment straight p subscript 1 plus increment straight p subscript 2 plus increment straight p subscript 3

space space space space space space space space space space space equals left parenthesis plus 6 space minus 6 space plus 12 right parenthesis

space space space space space space space space space space space equals space 12 space kg minus straight m divided by straight s

space space space space space space space space space space space equals space 12 space Ns

1949 Views

Is absolute rest or absolute motion possible?

Absolute rest and absolute motion is not possible because there is no point in the universe which is at rest and can be taken as point of reference. The planet Earth is in continuous motion. 
1986 Views

What is the most essential thing to study the motion of a body?

The most essential thing to study the motion is reference frame. Rest and motion are relative terms. It means that an object in one situation can be in rest but in another situation, the same object will be in motion. 
650 Views

What is rest?

When an object does not change its position with time, with respect to it's surroundings. In such a case the object is said to be at rest. 
1215 Views

Can a body be always at rest in some frame?

Yes, a body is always at rest in a frame which is fixed with the body itself. 
746 Views

What is motion?

When an object changes it's position with time, with respect to it's surroundings, the object is said to be in motion. 
657 Views