Q. 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 $3$ m/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 $(g = 10\, m /s^2)$ must be at least:
Solution:
elevater moving with constant speed hence
$T = 6800 + 9200 + 6000$
$T = 22000\, N$
power $= T·v = 22000 × 3$
$= 66000\, W$
