Is Force Ever a Function of Acceleration in Classical Mechanics?

[GreenLRan]

In class today, my professor said that you will never find a force that is a function of acceleration.

Why is this?


M$$\ddot{x}$$(t) = F(x,y,z,$$\dot{x},\dot{y},\dot{z}$$,t)
M$$\ddot{y}$$(t) = F(x,y,z,$$\dot{x},\dot{y},\dot{z}$$,t)
M$$\ddot{z}$$(t) = F(x,y,z,$$\dot{x},\dot{y},\dot{z}$$,t)

This is in a classical mechanics / dynamics course

 

[rock.freak667]

Usually forces vary with time, because acceleration would vary with time. I think he meant that you would not find a function such that F=2a²+a+3 as that would not work dimensionally.

 

[rcgldr]

What about a reaction force? For example a string attached to a ball and accelerating the ball, the force the ball exerts on the string is a function of the acceleration of the ball.

 

[rock.freak667]

What about a reaction force? For example a string attached to a ball and accelerating the ball, the force the ball exerts on the string is a function of the acceleration of the ball.

Well that is what I am saying, I think your professor meant that you would not usually measure force with acceleration or well plot force against acceleration.