Total torque exerted by a mass that falls in a circular pattern around a point.

[harry_4226]

Hi I have built a mass powered rolling vehicle but am having problems calculating the mathematical side of it.

Description of design: The vehicle is a wheel. I have cut little notches in part of the wheel to hold a mass on the outside circumference of the wheel. THe wheel is 0.175m radius. THe mass is 250g.

THe design works by initially the mass is placed at the top of the wheel at the highest point off the ground, where since the mass is sitting above the axis of rotation the wheel doesn't move. I then give it a little nudge foward and since torque is force multiplied by perpindicular distance, the mass causes the wheel to rapidly accelerate. When the mass reaches the lowest point of its cycle (when the mass touches the ground) the latch allows the mass to roll out and the wheel will continue rolling without the mass.

I need an equation that can find the total torque exerted by the falling mass as it falls around the circle. (The equation also takes into account the changing perpindicular distacne of the mass to the pivot point as it turns around the circle.

If anyone has an answer it would be greatly appreciated.

 

[harry_4226]

If this is too confusing i need an equation that can solve torque where there is a variable force.
Alternatively i need an equation that can solve torque when there is a variable perpendicular distance to the pivot.

 

[tiny-tim]

welcome to pf!

hi harry_4226! welcome to pf!

I need an equation that can find the total torque exerted by the falling mass as it falls around the circle.

no you don't … you only need conservation of energy

(of course you also need to know the moment of inertia of the wheel … if it's a solid disc, then that's I = mr²/2, and kinetic energy = Iω²/2 + mv²/2)