The motor for an elevator can produce 14kW of power. The elevator has a mass of 1100kg, including its contents. At what constant speed will the elevator rise?
Can anyone tell me how I can do this question? Thanks
Power is the rate of doing work = work /time = joules per second
Assuming no loss due to efficiency motor will do 14kj of work per second
weight = mass x gfs
gfs is approx 10N/kg
weight of lift = 11000N = 11kN force acting down
work = force x distance
lift can travel a distance of work/force = 14k /11k m/s
Power is work done per unit of time:
P = W / t
but we also know that work is force acting on a path:
W = F y
P = F y / t
where we can recognize ratio y / t which is in fact velocity of rising:
P = F v
from here:
v = P / F
v = 14000 / (1100 * 9.81) = 1.30 m/s
