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System of Particles and Rotational 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 coil has resistance 30 O and inductive reactance 20 O at 50 Hz frequency. If an AC source 200 V, 100 Hz, is connected across the coil, the current in the coil will be

  • 4.0 A

  • 8.0 A

  • fraction numerator 20 over denominator square root of 13 end fraction space A
  • 2.0 A 


A.

4.0 A

If space straight omega space equals space 50 space straight x space 2 straight pi space then space ωL space equals space 20 space straight capital omega
similarly space straight omega apostrophe space equals space 100 space straight x space 2 straight pi space then space straight omega apostrophe space straight L space equals space 40 space straight capital omega

straight i space equals space 200 over straight z space equals space fraction numerator 200 over denominator square root of straight R squared plus left parenthesis straight omega apostrophe straight L right parenthesis squared end root end fraction

equals space fraction numerator 200 over denominator square root of left parenthesis 30 right parenthesis squared plus left parenthesis 40 right parenthesis squared end root end fraction space equals space 4 space straight A
If space straight omega space equals space 50 space straight x space 2 straight pi space then space ωL space equals space 20 space straight capital omega
similarly space straight omega apostrophe space equals space 100 space straight x space 2 straight pi space then space straight omega apostrophe space straight L space equals space 40 space straight capital omega

straight i space equals space 200 over straight z space equals space fraction numerator 200 over denominator square root of straight R squared plus left parenthesis straight omega apostrophe straight L right parenthesis squared end root end fraction

equals space fraction numerator 200 over denominator square root of left parenthesis 30 right parenthesis squared plus left parenthesis 40 right parenthesis squared end root end fraction space equals space 4 space straight A
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Is it necessary for centre of mass to lie within the body?

No, centre of mass needs not to lie within the body. It is not necessary that the total mass of the system be actually present at the centre.

The position of the centre of mass is calculated using the usual Newtonian type of equations of motion. 
943 Views

What is the need of centre of mass?

Newton’s second law of motion is strictly applicable to point masses only. To apply the Newton's law of motion to rigid bodies, the concept of centre of mass is introduced.

The concept of centre of mass of a system enables us to discuss overall motion of the system by replacing the system by an equivalent single point object. 
911 Views

Is it necessary that there should be matter at the centre of mass of system?

No, it is not necessary that there be matter at the centre of mass of the system.

For e.g., if two equal point masses are separated by certain distance, the centre of mass lies at the mid point of two point masses and there is no mass at that point.
730 Views

Define centre of mass.

Centre of mass of a body or a system of bodies is a point at which the entire mass of the body or system is supposed to be concentrated. 
1449 Views

What is the significance of defining the center of mass of a system?

The motion of n particle system can be reduced to one particle motion.

An equivalent single point object would enable us to discuss the overall motion of the system. 
794 Views