**Answer:**

**3,010 W**

**Explanation:**

mass of elevator (Me) = 1700 kg

mass of counter weight (Mc) = 840 kg

travel distance (d) = 45 m

time (t) = 2.1 min = 126 s

What average power is required of the force the motor exerts on the cab via the cable?

from Newtons second law of motion

force exerted by the elevator motor + force exerted by the elevator counter weight = force exerted by the elevator cab weight

therefore

force exerted by the elevator motor = force exerted by the elevator counter weight - force exerted by the elevator cab weight

force exerted by the elevator motor (Fm) = (Me x g) - (Mc x g)

force exerted by the elevator motor (Fm) = (1700 x 9.8) - (840 x 9.8)

force exerted by the elevator motor (Fm) = 8428 N

average power exerted by the motor = Fm x speed

where speed = distance / time

average power exerted by the motor = Fm x (distance / time)

average power exerted by the motor = 8428 x (45/126) = **3,010 W**