- #1

Bittencourt

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I was reading a physics book and started to make some links, but i don't know if it's correct.

For example:

I need to calculate the power to move a car in a slide with friction. But as far as it's a car pulled by an motor, the motor provides the needes force to keep the speed.

I made the relations using moment:

Work = Moment and Work = Energy

M = F x wheel radius (this relation is between moment, pulling force and wheel radius of the car)

K = 1/2 m x v^2

Friction = m x μ x cos α

Horizontal component of weight: Px = m x sen α

So, I applied the forces (friction, horizontal component of weight and resultant force) in the wheel radius:

wheel radius x F - Friction x wheel radius - Px x radius = 1/2 x m x v^2

With this I found the force

W = F x d but I need to convert to [Newtons]

P = W/t

I would like to know if this relations are correct. As far as it isn't a conservative system, I got a bit lost.

I tried to get some numeric examples from the books to clarify, but I didn't find any example close to this. Only hypothetical systems that don't fit to reality.

What about the potencial energy, should I take in consider too?

Thank you very much!