A particle moves with a velocity vec v, = ,5hat{i} - 3hat{j} + 6hat{k},,m/s under influence of

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5.Work, Energy, Power and Collision

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A particle moves with a velocity $\vec v\, = \,5\hat i - 3\hat j + 6\hat k\,\,m/s$ under the influence of a constant force $\vec F\, = \,10\hat i + 10\hat j + 20\hat k$. Instantaenous power will be ............... $\mathrm{J} / \mathrm{s}$

A

$200$

B

$40$

C

$140$

D

$170$

Solution

Velocity $v=(5 i-3 j+6 k) m s$

and force $F=(10 i+10 j+20 k) N$

hence Power $P=F-v$

$=(10 i+10 j+20 k)(5 i-3 j+6 k)$

$=50-30+120$

$=140 \mathrm{W}=140 \mathrm{J} s$

Standard 11

Physics

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