# Calculating how fast a motor can move something in horizontal motion

1. Sep 17, 2011

### caljuice

1. The problem statement, all variables and given/known data
So I need a motor for a project. The motor i'm looking at creates circular motion. I want to make the motor move some object in a horizontal motion but I want to know how fast it can move the object horizontally before getting it. How can I find out how fast the motor can move it?
Motor in mind:
http://www.servodatabase.com/servo/hitec/hs-322" [Broken]

Sorry if there are unnecessary unit conversions. Seems like engines are explained in imperial units.

2. Relevant equations

Using this equation to find horsepower = (Torque x Engine speed (rpm)) / 5,252 = Horsepower
Found from:http://www.howstuffworks.com/question622.htm"

Torque for engine = 3.70 kg*cm = 0.03 kg per m = 0.22 lb/ft

speed = 0.15 sec/60° (not really sure what this is? Assuming 60 degrees every .15 sec. So one revolution (360 degrees) = 0.15 sec x 6 = .90 sec. Then rpm = 66.7

Mass of object being rotated =0.2 kg

3. The attempt at a solution

One way I thought of calculating this was converting the torque output to Power then converting power to work then to kinetic energy to velocity.

Horse power = 0.22 * 66.7 /5252 = .0028 horse power

Mechanical horse power = 33,00 lb*ft/min so (0.028 * 33,000)/60s= 1.54 lb*ft =2.09 n*m

I'll assume all work will equal KE. 2.09 J = 0.5 *0.2*v2

V= 4.6m/s.
Does it look right? Any help would be appreciated.

Last edited by a moderator: May 5, 2017
2. Sep 17, 2011

### rude man

Think about this: you said 'horizontal' motion. What if anything limits the velocity if you continually apply a certain amount of power to a mass moving horizontally?

BTW on the rhs equation of 'mechanical horse power' the dimension is energy, not power, so I would check that. Always check dimensions on any work you do. Every single term. I find more mistakes I make that way than with any other, by a mile!

3. Sep 17, 2011

### caljuice

I'm guessing you mean drag and friction? Would it still affect it a lot with the device being so small? I don't think I would be able to calculate it with the information I'd have.

Sorry isn't it in energy already? 2.09 Nm is Joules.