Calculating starting/tractive force

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To calculate the force needed to overcome inertia for a 1500 lb sliding door, the initial calculation of 93.74 lbs is based on acceleration without considering friction. To include friction, the resistance force is determined by multiplying the weight of the door by the coefficient of friction, which requires adjusting for the four wheels to ensure even load distribution. The correct formula incorporates both friction and acceleration: F = m(0.02g + a), where g is 9.81 m/s² and m is the mass in kg. After calculations, the total force required amounts to 176 N or approximately 40 lbs. Understanding these dynamics is crucial for accurate force calculations in similar applications.
snwright
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Hey all-

First post here!

I need to calculate the force required to overcome inertia of a 1500lb object. It's a sliding door, which rolls on 4 identical wheels, each with a coefficient of friction of .02. I'd like to make it accelerate to .25m/s over a period of 4 seconds.

I think what I need OMITTING FRICTION is: F=Ma = 6672 N * .0625m/s2 = 417 N = 93.74 lbs. Is that accurate? How do I include the resistance due to friction?

thanks!

Spencer
 
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Resistance due to friction is weight of door times coefficient of friction. You need that much additional force. Be careful about how you consider the four wheels.
 
How should I be considering them? The load should be distributed pretty evenly across all four wheels. I was thinking that it would be a wash, and that the accumulated drag would be .02.
 
You need to add all the resistance forces to the inertia. The force needed would be:

F = 0.02mg + ma = m (0.02g + a)

g is 9.81 m/s² and the SI unit for m is kg not N (So 1500 lb is 680 kg). F = 176 N = 40 lb.
 

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