Dynamics of Circular Motion

We know that circular motion can be both uniform and non-uniform. If the tangential component of acceleration is absent, it will be uniform circular motion, and if the tangential component of acceleration is present, it will be non-uniform circular motion. In case of non-uniform circular motion, the net acceleration of the particle is the resultant of radial acceleration and tangential acceleration.

Circular Motion

Now, suppose you are in an inertial frame of reference and you are observing a particle in a circular motion. The net force on the particle must be non-zero according to the second law of motion since the particle has some acceleration. Let’s take the case of uniform circular motion. The speed of the particle is constant, and the acceleration of the particle towards the centre is v2/r.

Let the mass of the particle be m. From the second law of Newton, we can say that

F = ma

F = m(v2/r)

This force is directed towards the centre and is therefore known as centripetal force. This centripetal force is required to keep the object in a uniform circular motion. This is just the name given to this type of force and this centripetal force can arise from tension, friction, etc.

Circular turnings on roads

When a vehicle turns on roads, they travel along a circular arc. The only forces acting on the vehicle are:

1) Weight Mg
2) Normal reaction force N
3) Friction

If the road is horizontal, the first two forces must be in a vertical direction. Therefore, the only force that can provide the radial acceleration for turning is friction. In this case, the force of friction acts as the centripetal force.

F = m(v2/r)

Since there is a limit to the maximum value of friction, for a safe turn,

\(\begin{array}{l}m \frac{v^{2}}{r} \leq µ_s N\end{array} \)

where,

µs = coefficient of static friction

Watch the video and learn more about the application of circular motion

Frequently Asked Questions – FAQs

Q1

What type of motion is called circular motion?

The motion of an object in a circular path along the circumference of a circle or rotation along a circular path is called circular motion.
Q2

What are the types of circular motion?

Circular motion can be either uniform or non-uniform.
Q3

Give an example of circular motion?

The movement of the satellite in a circular orbit, ice skaters going in a circle with constant velocity, and cars moving in a circular path are examples of circular motion.
Q4

What is the value of instantaneous acceleration in a uniform circular motion?

The instantaneous acceleration in a uniform circular motion is given by
a = v2/R
where v is the velocity of the object and R is the radius of the circular path.
The direction is perpendicular to velocity and directed inwards along the radius.
Q5

What is the tendency to be overturned by a cyclist if he turns around a curve at 15 miles/hour and if he doubles the speed?

From the formula, we know that F = mv2/R.
This means that F ∝ v2.
Therefore, it can be said that if v becomes double, then F will become four times. So the tendency to overturn is quadrupled.

The below video provides the Top 10 NTSE Important Questions on Motion Class 9

To learn more about the dynamics of circular motion, get connected to BYJU’S Classes.

Test your knowledge on Circular motion

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