Chapter - unit and dimensions
Q-Power of motor is 200W.If the unit of length is halved,that of mass is doubled and that of time is also doubled, then power of motor in new system is?
1.3200W
2.3200 new unit
3.12.5 new unit
4.12.5W
 
 
Ans. 3200 new unit.
sir please explain it..

Asked by rakshitreshu1997 | 5th Aug, 2015, 07:26: PM

Expert Answer:

begin mathsize 12px style Power space equals space Work over Time space equals space open square brackets straight M to the power of 1 space straight L squared space straight T to the power of negative 3 end exponent close square brackets 200 space straight W space equals space fraction numerator kg space cross times space open parentheses straight m close parentheses squared over denominator open parentheses straight s close parentheses cubed end fraction When space unit space of space length space is space halved comma that space of space mass space is space doubled space and space that space of space time space is space also space doubled comma space then space power space of space motor space in space new space system space will space be comma 200 space straight W space equals space fraction numerator 2 space kg asterisk times space cross times space open parentheses begin display style fraction numerator straight m asterisk times over denominator 2 end fraction end style close parentheses squared over denominator open parentheses 2 straight s asterisk times close parentheses cubed end fraction space 200 space equals space fraction numerator 2 cross times begin display style 1 fourth end style over denominator 8 end fraction space kg asterisk times straight m squared asterisk times straight s to the power of negative 3 end exponent asterisk times Power space equals space 3200 k g asterisk times straight m squared asterisk times straight s to the power of negative 3 end exponent asterisk times equals space 3200 space new space unit end style

Answered by Priyanka Kumbhar | 7th Aug, 2015, 11:18: AM

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