NEET Physics Solutions For Class 11 Centripetal Force

Centripetal Force

Centripetal Force: In uniform circular motion the force acting on the particle along the radius and towards the center keeps the body moving along the circular path. This force is called centripetal force.

Centripetal Force Explanation:

1. Centripetal force is necessary for uniform circular motion.
2. It is along the radius and towards the center.
3. Centripetal force = [mass] × [centripetal acceleration] = \(\frac{m v^2}{r}=m r \omega^2\)

4. Centripetal force is due to known interaction. Therefore it is a real force. If an object tied to a string is revolved uniformly in a horizontal circle, the centripetal force is due to the tension imparted to the string by the hand.

When a satellite revolves in a circular orbit around the Earth, the centripetal force is due to the gravitational force of attraction between the satellite and the Earth.

In an atom, an electron revolves in a circular orbit around the nucleus. The centripetal force is due to the electrostatic force of attraction between the positively charged nucleus and the negatively charged.

Question 1. A stone of mass 1kg is whirled in a circular path of radius 1 m. Find out the tension in the string if the linear velocity is 10 m/s.
Answer: Tension

⇒ \(\frac{m v^2}{R}=\frac{1 \times(10)^2}{1}=100 \mathrm{~N}\)

Question 2. A satellite of mass 107 kg is revolving around the earth with a time period of 30 days at a height of 1600 km. Find out the force of attraction on satellite by Earth.
Answer:

Force = \(\mathrm{m} \omega^2 R \text { and } \frac{2 \pi}{\mathrm{T}}=\frac{2 \times 3.4}{30 \times 86400}=\frac{6.28}{2.59 \times 10^6}\)

Force = \(m \omega^2 r=\left(\frac{6.28}{2.59 \times 10^6}\right)^2 \times 10^7 \times(6400+1600) \times 10^3=2.34 \times 10^5 \mathrm{~N}\)

Centrifugal Force

The pseudo force experienced by a particle performing uniform circular motion due to an accelerated frame of reference which is along the radius and directed way from the center is called centrifugal force.

Centrifugal Force Explanation:

1. Centrifugal force is a pseudo force as it is experienced due to accelerated frame of reference. The interaction of origin and away from the centre.
2. It is along the radius and away from the centre.
3. The centrifugal force in having the same magnitude as that of centripetal force. But, its direction is opposite to that of centripetal force . It is not due to reaction of centripetal force because without action, reaction not possible, but centrifugal force can exists without centripetal force.
4. Magnitude of the centrifugal force is \(\frac{\mathrm{mv}^2}{\mathrm{r}} \text { or } \mathrm{mr} \omega^2\)

Note: Pseudo force acts in a noninertial frame i.e. accelerated frame of reference in which Neutron’s laws of motion do not hold good.

• When a car moving along a horizontal curve takes a turn, the person in the car experiences a push in the outward direction.
• The coin placed slightly away from the center of a rotating gramophone disc slips towards the edge of the disc.
• A cyclist moving fast along a curved road has to lean inwards to keep his balance.

Difference Between Centripetal Force And Centrifugal Force:

Applications Of Centrifugal Force: The centrifugal pump used to lift the waterworks on the principle of centrifugal force.

A cream separator used in the diary work works on the principle of centrifugal force. Centrifuge used for the separation of suspended particles from the liquid, works on the principle of centrifugal force. Centrifugal drier.