An elevator in a building can carry a maximum of 10 persons, with the average mass of each person being $68 \mathrm{~kg}$. The mass of the elevator itself is $920 \mathrm{~kg}$ and it moves with a constant speed of $3 \mathrm{~m} / \mathrm{s}$. The frictional force opposing the motion is $6000 \mathrm{~N}$. If the elevator is moving up with its full capacity, the power delivered by the motor to the elevator
$\left(g=10 \mathrm{~m} / \mathrm{s}^{2}\right)$ must be at least:
Correct Option: , 4
(4) Net force on the elevator $=$ force on elevator
+ frictional force
$\Rightarrow \quad F=(10 m+M) g+f$
where, $m=$ mass of person, $M=$ mass of elevator,
$f=$ frictional force
$\Rightarrow \quad F=(10 \times 68+920) \times 9.8+600$
$\Rightarrow F=22000 \mathrm{~N}$
$\Rightarrow P=F V=22000 \times 3=66000 W$
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