An elevator in a building can carry a maximum of 10 persons, with the average mass of each person be

Question

An elevator in a building can carry a maximum of 10 persons, with the average mass of each person being 68 kg . The mass of the elevator itself is 920 kg and it moves with a constant speed of $3 \mathrm{~m} / \mathrm{s}$. The frictional force opposing the motion is 6000 N . If the elevator is moving up with its full capacity, the power delivered by the motor to the elevator ( $g=10 \mathrm{~m} / \mathrm{s}^{2}$ ) must be at least\

Professor PC Thomas Classes · Answer

(b) : Number of persons $=10$, mass of each person, $m=68 \mathrm{~kg}$, mass of 10 person,\ $m^{\prime}=680 \mathrm{~kg}$ mass of elevator, $M=920 \mathrm{~kg}$, speed, $v=3 \mathrm{~m} / \mathrm{s}$ frictional force, $f=6000 \mathrm{~N}$, $g=10 \mathrm{~m} / \mathrm{s}^{2}$\  Net force, $F=M g+m^{\prime} g+f$\ $=9200+6800+6000=22000 \mathrm{~N}$\ $	herefore \quad$ Power $=$ force $	imes$ velocity\ $=22000 	imes 3=66000 \mathrm{~W}$\