# Calculate the power of a the lift motor

#### taomay

Calculate the power of a the lift motor,when is lift on a distance on a building site lift 400kg of brick50m to the top of a buiding in 24 seconds

Ans ?

Regards.
taomay

Related Biology and Chemistry Homework Help News on Phys.org

Staff Emeritus
Homework Helper
You tell us.

#### taomay

Calculate the power of a the lift motor,when is lift on a distance on a building site lift 400kg of brick 50m to the top of a buiding in 24 seconds

Ans ?

Regards.
taomay

Ans :

mass= 400kg (convert mass to weight 1kg=9.81N (force of gravity on 1kg)

400x9.81=3924N
Workdone (j)= force xdistance
3924x50 =196200

Power = 196200 /24= 8175 W
convert to KW =8.175KW

Assuming that this is a cable driven lift and not a hydraulic lift, more data is required to calculate the HP required to lift the load:
Desired speed of lift
% of counterweighting
Hoisting machine eff.
acceleration rate and rate of change of acceleration rate (known as jerk rate)
Hoistway eff.
H.P. required = Speed (fpm) x capacity (lbs) x Percentage of uncounterweighted load (usually .4 to .5 / 33000) / overall eff.*
* this can actually range anywhere from 40% to 90% depending upon machine be geared or gearless, the roping type usually being 1:1 or 2:1 as well as the types of guide shoes (roller or slide).
If steep accelleration and jerk rates are required to meet a specific performance than a larger motor maybe required to meet those peak torque requirements.
To convert HP to KW, multiply the HP times .746

### Physics Forums Values

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving