Hi everyone,

I am an under graduate mechanical student. I have problem in a certain calculations. Actually I have to calculate the speed of a shaft connected to a pinion which is being moved by a rack which is pressed by a ramp downwards (load on a ramp can very from 1000kg to 10000kg)

All sugesstions are kindly invited and extoled

Thank you

Since you gave no detail all I can suggest is to determine forces and moments acting on each element and use \vec F = m \vec a and \vec T = I \vec \alpha to find the resulting motion.

thank u for your response
actually I have to calculate shaft speed this is a project on speed breaker electricity generation as it is well known so I am doing calculations on it please refer this link for further view of this project[URL="http://www.ipcbee.com/vol1/55-B10014.pdf"]
the only difference is that I want to calculate shaft speed not power generated

I read the article. There are some fundamental flaws in the author's mathematics, so I'm surprised if this has actually been published. For example he uses the term "power" incorrectly. If the mechanism generates 4 watts of power that's the rate of energy generation - it makes no sense to talk about power generated "per minuite" or "per 24 hours." He confuses power with energy.

Nevertheless, assuming that energy can be stored in the flywheel so as to provide continuous power output through the generator of around 4 watts the speed of the shaft will depend on the amount of mechanical energy stored in the system that is available for electricity generation. The stored mechanical energy is the difference between energy input (about 245 joules per vehicle that passes by), and the amount of electrical energy produced. This stored energy is in the form of the spinning flywheel, so

E = \frac 1 2 I \omega^2

Given values for E and moment or inertia of the flywheel 'I' you can determine the rotational speed \omega.

Very well observed power is already in watts i.e. joules per second so power per second makes no sense


Thank u very much
This helps a lot

Why I is moment of inertia of a flywheel not shaft

if E is 980 joules then I will be (pi*d^4)/64 the omega seems to come 222024.33 rad per sec this is ridiculous I can't calculate it

please help

Please show how you calculated this. What do you have for moment of inertia 'I' of the flywheel? You wrote I= (pi d^4)/64, but that's incorrect - note that the moment of inertia should be in units of Kg-m^2, not m^4.

As for why I said I to use the moment of inertia of the flywheel, and you asked why not the shaft (I assume you mean the shaft the fly wheel is attached to) - yes, you can incude the shaft's moment of inertia as well. I didn't mention it because the moment of inertia of the shaft is probably very small compared to the flyweel.

Thank u I got it