A) 27
B) 81
C) 561
D) \[{{\left( \text{9}.\text{3489} \right)}^{\text{3}}}\]
Correct Answer: A
Solution :
If the volume of water obtained becomes \[n\] times, the velocity with which the water is ejected from the same pipe must also become \[n\] times because, volume \[=\] area \[\times \] velocity, and area remains same. If volume becomes \[n\] times, the mass of the water ejected also becomes \[n\] times. Now, to think about the power of motor, the most suitable formula for the given variables may be taken as rate of change kinetic energy. \[P=\frac{1}{2}m{{v}^{2}}\]or\[P\propto \frac{m{{v}^{2}}}{t}\] As decided above, \[\frac{m}{t}\] has become n times, so power becomes \[{{n}^{3}}\] times. Hence in the given problem \[\frac{P'}{P}\] becomes\[{{3}^{3}}\]\[=27\,\,times\] Note that, in such problems force becomes\[{{n}^{3}}\]times
You need to login to perform this action.
You will be redirected in
3 sec
