# How to nullify effect of Centrifugal force/centripetal force

I have a track over which a rectangular object moves. The object holds sensitive material which should not move too much. Then there is a 90 degree turn of the track with some radius of curvature. When the object moves through this turning it experiences centripetal/ centrifugal force which moves the sensitive material over the object outwards. If i use a circular object to carry my sensitive material, and rotate it in the opposite direction will it nullify the centripetal/ centrifugal force on the turning?

It will never 100 % remove the centrifugal effect. No matter how you design it, your material must decrease its parallel speed to zero and increase a sideways speed from zero. This requires a momentum change. And a momentum change requires force. It is this centripetal force which you are trying to avoid, if I understand your question right.

Although you can't avoid it 100 %, you may be able to reduce it in magnitude. The force done is momentum change over time:

$$\sum F=\frac{\Delta p}{\Delta t}$$

Since the change in speed and also the mass are constant, the momentum change is also constant due to $p=mv$. The only thing left for you to work with is an increase of the duration $\Delta t$.

• The use of a circular platform that you suggest, may have a positive effect if you are able to control that motion, i.e. with an electric engine or so. Because that platform can then start moving the object sideways at a slower acceleration, before the turn has been reached. The momentum change is then initiated a bit before it would otherwise be, give a longer duration for it to happen. Basically, this feature would extend and flatten the curved path which the material is taking.

• Alternatively, you could consider the use of springs to dampen the "push" from the cart. The cart turns and pulls the material along with it - a stiff spring of some sort would decrease the initial force and would slowlier extend back to original length, thereby extending the duration.

You will only nullify the centrifugal force if the rotation which you apply enables the sensitive material (SM) to continue moving in the same straight line. This would not be useful if it is your intention to transport the SM along a curved path.

If the SM moves along a non-linear path then centrifugal force is inevitable : it cannot be eliminated, only minimised. (But see below regarding gravity.)

The force on the SM depends on its acceleration. So what you need to do is minimise its acceleration. Along a straight path you should change its speed as slowly as possible. When it travels round a bend with radius $r$ at speed $v$ its acceleration is $\frac{v^2}{r}$. To minimise acceleration around the bend make the radius large and the speed low.

The SM is already subject to an upward force, the normal reaction opposing gravity. Additional acceleration will add to this as a vector. You need to avoid the total acceleration exceeding the limit which the SM can withstand. So you should particularly minimise any acceleration which is upward - eg at the bottom of a vertical loop.

Sudden changes of acceleration ("jerk") can also create large forces and should be minimised by making smooth gradual changes to the motion. See Bidirectional jerk motion on a stopping vehicle.

Note:

It is not actually the amount of centrifugal/centripetal force which is damaging but the manner in which it is applied to your body.

Free-falling at $30g$ in a uniform gravitational field is not damaging at all, but being accelerated at $30g$ in a rocket in space is damaging. The difference is that gravity pulls on every atom in your body equally, so no part of your body pushes against any other. You do not get squashed, you feel weightless. Whereas the rocket pushes on your back or feet and this contact force is transmitted through your body, one part pushing on another - you do get squashed.